The role of the Blessed Virgin Mary in God's plan of Salvation lies in one major reality: Mary is the only human creature after the fall to have a DIRECT PERSONAL relationship with each Person of the Divine Trinity.
Each honor given to Mary rises from this reality and moves logically from it as well. The Dignity of Being the Mother of God, her Immaculate Conception, her Perpetual Virginity, Spiritual Motherhood, Assumption into Heaven and Coronation as Queen of Heaven all stem from the reality that Mary is touched directly in a Personal Relationship with the Divine Trinity. All we have from Salvation is a Direct Personal relationship with God the Son and God the Holy Spirit. Only when in Heaven do we receive a direct personal relationship with God the Father.
I will attempt to clarify each privilege given to the Blessed Virgin Mary that proceeds from the reality of her Direct Relationship with God the Father as well as with the other Divine Persons.

Divine Motherhood

God the Father eternally generates God the Son. This relationship means that God the Son had to be generated by God the Father in the human body of Mary to be the Mother of God. God the Father had to Personally generate the God the Son in Mary. That means God the Father had to Personally touch Mary in a special Personal relationship that Generates God the Son inside of Mary. That she is Conceived by the power of the Holy Spirit does not mean more than God the Son dwells in Mary, which is the Personal Relationship of God the Holy Spirit. The Holy Spirit does not generate but dwells in Mary Making the Motherhood of Mary a Personal Relationship with each Divine Person of the Trinity.
The Personal relationship of God the Father has permanent consequences in the life the Blessed Virgin Mary. All the privileges extended to Mary follow directly from this unique relationship with God the Father.
Immaculate Conception
Mary needed to be saved and redeemed as she is a human creature. There is need to be freed from the Stain of Original Sin extended to all humanity after the fall and the loss of any Direct Relationship with God the Father. The only way Mary could have a Personal Relationship with God the Father is for her to be Redeemed by God the Son anticipating His Saving Act of Death and Resurrection at the very moment of her Conception. Only then is she able to have a Direct Personal Relationship with God the Father and allowing God the Father to Generate His Son inside her body.
That is what the Doctrine of the Immaculate Conception teaches. God the Son frees Mary of any stain of Original Sin by anticipating the fruit of His saving Act, therefore Redeeming her of any Stain of Sin from the first moment of her existence.
That she remains free from sin is from her freely choosing to follow God and His Will throughout her life. She lived a life freely choosing to be the Handmaid of the Lord and that especially at the moment she accepts becoming the Mother of God. Her being able to be Directly Touched by God the Father is made possible only by what we understand by the Immaculate Conception.

Perpetual Virginity

Mary is a Virgin before, during and after the birth of Jesus, the Son of God and her Son. That is what we mean by the concept of Perpetual Virginity in the life of Mary, the Mother of God.
That she is a Virgin before the Angel Gabriel came to ask Mary if she would be the Mother of God is believed by almost all Christians. That she was "betrothed" to Joseph is accepted and held by most as well. We must remember what Betrothal means in the Jewish society. It means that a couple are called to marriage and are making plans to complete the marriage with the accepting of the bride into the household. It is then that the marriage is consummated and the marriage realized.
In the case of Mary and Joseph we find they are betrothed. Mary has not yet come into the house of Joseph and therefore is still a virgin. But Mary had a visitor come from Heaven and asked her if she would accept being the Mother of God. Mary says her fiat: "be it done to me according to your word."
At that very moment God the Father in PERSON directly touches Mary and Generates God the Son with Mary. The entire Femininity of Mary is touched by God the Father. In biblical terms God the Father knows Mary and she has a Son. This direct relationship of God the Father with Mary consumes her capacity of Motherhood. Every aspect of her femininity is touched and contacted by the Divine Person of God the Father. In simple terms God the Father and Mary have consummated an eternal marriage. She is now incapable of having a normal human marriage because she belongs to God the Father in a Personal Eternal relationship.
This gives us understanding more of what the scripture tells us of Joseph. The scriptures say Joseph is a Just man and betrothed to Mary. Learning that Mary is with child he thinks of quietly dismissing Mary but is told in a dream to accept Mary as his wife. That the child she bears is the Son of God and not the son of any other man. Joseph accepts Mary into his house and they have a real marriage. How is this a real marriage without consummating the marriage act together? That is where the dignity of Joseph is found and realized: He Accepts the Paternity of God. His accepting of Mary into his house is the acceptance of God as the Father and realizes the consummation of their marriage is in this acceptance of the Paternity of God. He realizes his role is to be the husband of Mary protecting her Virginity and accepting her Son as his Son because he accepts God as the Father. He realizes that Mary has a unique and personal relationship with God and finds from her the same Personal relationship by becoming the father of God the Son.
Mary remains a Virgin in giving birth to her Divine Son. This is believed and held by most Christians. Somehow the natural birth of Jesus does not violate her Virginity. God the Father is the Father who generated his Son in her, God the Holy Spirit dwells and brings forth freely and naturally God the Son retaining the virginity of Mary.
After giving birth to Jesus Mary remains a Virgin as she remains totally consumed with the personal relationship with God the Father. Joseph is the protector of this Virginity by his free and total acceptance of the Paternity of God and the relationship between God and Mary, his wife. Their marriage is realized in the consummation made between God the Father and Mary and accepted by Joseph through the message of a dream.

Spiritual Motherhood

The unique marriage of Joseph and Mary highlights the Spiritual Motherhood of Mary. As the Mother of God she continues to maintain a personal relationship with God the Father . This relationship is what makes the Marriage between her and Joseph a real marriage in all human understanding of marriage. It also shows the task of Joseph to be more than just a necessary act for human norms. It is a true marriage and a true family that is unique in its direct relationship with God the Father. The spiritual bond with all humanity grows from this relationship. All humanity is made new with this relationship and realized in the Divine Mission of Jesus the Son of God and Son of Mary. Both Mary and Joseph take part in the Family of God. That Family of God is the Mission of Jesus: to reunite God and Humanity in Eternal Happiness. The mission of Jesus is to bring Humanity to the Father and to those who accept to unite them with the Father. In Heaven there will be a Personal Relationship with God the Father brought forth by the Personal Relationship with God the Son and God the Holy Spirit. This relationship already exists in Mary and therefore she is the Spiritual Mother of all those who accept Jesus and His mission in their lives.
This Spiritual Motherhood was made known clearly at the foot of the Cross when Jesus gave Mary to be the Mother of the Beloved Disciple.

Assumption

When the earthly mission of Mary was completed she was "taken up into Heaven, body and soul".
Because Mary never was touched by the stain of sin she does not receive the penalty of death and corruption. Mary is taken into Heaven by the power of God and this we call the Assumption. She is assumed because she is simply a creature and not divine. It is not by her own power but by the power of God and rightly given to her because of the unique relationship she has with Each Divine Person.
Because the Maternal relationship exists eternally in Mary with God the Father, God the Son and God the Holy Spirit, she is eternally present with the Father and the Son and the Holy Spirit both in body and soul. This is natural because of the consummated marriage retains with God the Father and also why it is believed by many that Joseph is also in Heaven in a special way, that is body and soul. This we only speculate about Joseph but does give understanding why Joseph is considered a Universal Patron of humanity.

Queen of Heaven and Earth

This title to Mary comes naturally with the position of Mary as the Mother of God. Mary is the Queen Mother of Jesus the King of Kings. Because of her unique and complete relationship with God the Father makes her the Queen Mother and the fruit of her Womb is Jesus, the Son of God and King of Kings.


Conclusion

From what has been present above we can only conclude that Mary is a very unique woman. This unique woman is the only human person to have a direct relationship with the Divine Trinity. This relationship exists in Mary from the first moment of her existence into eternity. No other human creature has this relationship.
That Mary is therefore honored with various titles and privileges comes from God and known by humankind because God loves to have his Blessings known and admired.
That Mary is completely human and needs Salvation is known and accepted but that because of her unique relationship with the Trinity she is a powerful aid for humanity to learn and accept God's Salvation. I simply hope this small essay helps others to understand the unique position of Mary with God and with God's human Family.