At what point do we worry about who Mary of Magdalene was? To phrase it a different way, "Scripturally, who is Mary Magdalene and does it matter?"
Western and Eastern traditions vary on the matter. The Scriptures indicate 3 Marys and in the West we try to tie them together: possessed, sinner, disciple.
We may celebrate the progression she represents; we may celebrate only her final role as disciple and first announcer of the Good News; we may try to make sense of things that make no sense. We may try many things but they only bog us down when considering who we think she is.
The important thing to me and the importance of her feast (again, to me) is who Jesus thought she was, and thanks to the Communion of Saints, who she is.
In John, she among all of the Apostles and disciples, is first at the tomb. In the Synopics, she is mentioned first in any list at the tomb. In John, she alone speaks with Jesus. In all she returns with the message from God.
What strikes me is that in all situations she alone, though blinded by grief, seeks Jesus.
Jesus had deep loving relationships (think about the use of agape and philo in John 21:15-19). Mary and Peter often figure as the first in any list. That tells me a lot. No matter how she came to the Lord, according to Scripture, she remains out front, even before Peter.
On the first day of the week, Mary of Magdala came to the tomb early in the morning, while it was still dark, and saw the stone removed from the tomb. So she ran and went to Simon Peter and to the other disciple whom Jesus loved, and told them, “They have taken the Lord from the tomb, and we don’t know where they put him.” ...Then the disciples returned home. But Mary stayed outside the tomb weeping. And as she wept, she bent over into the tomb and saw two angels in white sitting there, one at the head and one at the feet where the body of Jesus had been. And they said to her, “Woman, why are you weeping?” She said to them, “They have taken my Lord, and I don’t know where they laid him.” When she had said this, she turned around and saw Jesus there, but did not know it was Jesus. Jesus said to her, “Woman, why are you weeping? Whom are you looking for?” She thought it was the gardener and said to him, “Sir, if you carried him away, tell me where you laid him, and I will take him.” Jesus said to her, “Mary!” She turned and said to him in Hebrew, “Rabbouni,”* which means Teacher. Jesus said to her, “Stop holding on to me, for I have not yet ascended to the Father. But go to my brothers and tell them, ‘I am going to my Father and your Father, to my God and your God.’” Mary of Magdala went and announced to the disciples, “I have seen the Lord,” and what he told her.
-- John 20:1,2,10-18