I remember the day I actually understood the Immaculate Conception - I was walking out of the subway and literally stopped in my tracks when I realized that for Mary to have the exact same Free Will that Eve did when choosing to obey or disobey God, she would have to be in the same spiritual state, i.e., free from the taint of Original Sin.
To take it a step further, for Mary to be “blessed among women,” she must be superior IN ALL WAYS to Eve.
It’s all very clearly spelled out in Genesis 3:15 and the first chapter of the Gospel of Luke.