Mary’s consent was given, as was that Moses, Peters, etc. after their protests, and she could have refused, yet the issue is that this does not render her the saint on steroids Catholics make her to be as compared to those whom the Holy Spirit testified far more of (even in the gospels Mary is quite marginal).
Mary is an example of a holy and surrendered vessel of God in carrying and caring for the Word made flesh, and blessed by being so chosen, but which did not require her to be sinless anymore than it was necessary for those to be who brought forth the wholly inspired Words of God, or the nation of Israel, “of whom as concerning the flesh Christ came.” (Rm. 9:5)
And the error is in exalting Mary “above that which is written,” (cf. 1Cor. 4:6)
Mary is not shown and laboring day and night for years in the care of all the churches, and suffering great persecution as she did so, or constantly feeding the church with her words, or even being a worker of many miracles and being an instrument of healing for many.
Instead, the most preeminent example of this, after the Lord Jesus, is the apostle Paul, who is relatively marginalized by Rome behind Mary and others.
Considering the unwarranted excess of attributions given to Mary by Catholics wresting Scripture, one can only imagine what more they would do if even 10% of the manifestations of the above attributes was given to Mary.
The prime point made by Catholics is that Mary's consent was supremely pivotal and was the "first cause," the indispensable act of will that made everything else possible.
Mary consented because it was God who reveal His will as concerning her.