Yet, she seemed kind of doubtful when told her role, and later seemed surprised when Jesus was hanging out at the temple.
Why would his mother think he was out of his mind if she were without sin and knew from the beginning who he was? Why would she have shown doubt?
Further, once she shows up, Jesus doesn't show her any preference or overt favor - he doesn't run right out to greet her. No, in fact, he stays inside and says, "Who are my mother and my brothers? These are my mother and my brothers. Everyone who obeys the word of God is my mother and my brother and my sister." (I'm paraphrasing from Matthew).
Jesus does not show any preference to Mary. When she asks him about the wine at Cana he doesn't jump right up and do what she asks. In fact, it's almost a rebuke. He says, "Woman, what does this have to with us?". He ultimately agrees to help out, and performs a miracle, but he almost acts annoyed by her request. His time had not yet come.
Mary is mentioned all of six or seven times in the New Testament. Apart from the beginning of Luke, the Magnificat, there isn't a whole lot more about her. We know she was with him at various points, and among the "women" who followed him, and was in Jerusalem during the Crucifixion. But none of the New Testament writers show that she had any special role or position apart from agreeing to cooperate with God in giving birth to the Messiah. This makes her a wonderful and blessed girl, and mother, but apart from that special respect and memory, every other thing about her that the Catholic Church developed as doctrine is simply baseless.
It doesn't take any deep searching of history to quickly determine that the pagans coming into Christianity in Ephesus in the 2nd century latched on to Mary and that the cult of Mary developed out of those Christians who came out of goddess worshiping cults and were looking for a substitute.
It wasn't any kind of conspiracy or anything deliberately malevolent. In my view, and from everything I've read, it simply was an organic process that set in, and the more focus placed on Mary, the more important she became, leading to even more focus on Mary, etc. All of this set up a cycle of increasing attention paid to Mary, eventually justifying "prayers" to Mary and all the additional doctrines that came along after.
This does not remove the fact that it isn't a true part of Christianity, it's unbiblical, it takes away from the Son, it focuses worship (prayer, in my view, and the view of many others, is a form of worship) on the creature not the creator, and it's a big, unnecessary distraction in general. There is no historical basis for it. There's definitely no scriptural basis for it.