[b:1wj9s16y]Why didn’t you or I receive this singular grace? Do we not have roles in this world? Does he not want us to be saved?[/b:1wj9s16y]
I was privy to an interview by a bishop who had been tortured and in prison for defending the Faith once. He was asked, “Do you think you would have been happier to have lived in the century before Communism where the Church and clergy where treated with respect rather than scorn?” His reply was, “No, God in His wisdom chose from all eternity for me to share His suffering, and show His grace to people who needed the encouragement.” So now that I think I better understand your question, I’ll try to give my answer……
Our Lady as I already mentioned every moment of her existance bowed down to the will of God. She did so of her own free will.
God knowing that none of us had the same faith and fortitude did not choose us. While we do like our Lady posess free will, He also knew our weaknesses and the graces needed for us to cooperate with His will. Even if only one person would accept His will, He would have been willing to become incarnate, die, and send His graces to all of us so that one person could spend eternity with him. As it is a very rare gift to be able to see the condition of someone’s soul, (St. John Marie Vianney and St. Padre Pio are two examples that come to mind) we are also not privy to what God will consider when it comes to judging our neighbor, (A little off topic I know).
Boiling it down, God knows us and our strengths and weaknesses. Knowing that (as far as we know) our Lady is the only human in history that would be obedient every moment of her life, He used that to choose her to ensure His plan for our salvation. Knowing that we would not be, he did not choose us for that singular grace.
I started to type the following in an earlier answer, but not understanding your question did not. I had a professor in College, a Dominican priest who was a well respected theologian. He one day diverged off topic and began discussing Speculative Theology. An area where theologians develop theories and study what the early Fathers wrote about different subjects that have not been formally defined by the Magesterium. He told us about a theory held by some theologians that our Lady could have been only one of thousands of women considered for the special graces to become the mother of our Lord. She was simply the first and only to accept the role. They further speculated that two other things occured, those who rejected the offer did not retain a memory of the offer and that if the theory is true it is one of many things that God has chosen not to reveal to us in this lifetime.
The above theory does not deny our Lady’s special place in history. It does not proport to be dogma, and does not reject the defining dogma of the Immaculate Conception. It simply is one of the (little known) theories that theologians have batted about as to how the plan of salvation could have been implimented.