This is such a terrible misunderstanding, and of course includes proof texts of things misunderstood (who doesn’t do this at some point?).
First off, no, Mary is the immaculate conception. This means she was conceived without sin as she was not merely chosen to be the mother of Christ but was created with this express purpose in mind.
She did not sin, and we have no reason to think this. The context of the Bible is one with great exaggeration. When we hear “all have sinned” we know it to not be an absolute statement of literal fact, why? Because Jesus did not sin, clearly.
Now, onto specifics.
Mary is hailed by the angel in Luke. This is something done only to royalty in this time.
The angel says to her, “Hail, Full of Grace”.
This term, in Greek, translated full of grace is a term appearing only once else in the Bible, describing the baptised believer in Jesus Christ, as you say, one whose slate is wiped clean and is without sin.
Now, I hope you see how this is important: Jesus was not yet born, and yet to establish the Sacrament of Baptism, etc.
Yet, she was in a state of sinlessness prior to this. This only makes sense, that she was sinless and imputed no original sin onto Jesus, who was like us in all things but sin.
Later, we see her cousin say, guided by the Holy Spirit, the Lord is with you, blessed art thou among women.
And Mary says of herself, in the Bible, that
"All generations shall call me blessed," which I don’t feel like you’re doing when you call her a “dead sinner”.
And then she says, “My soul magnifies the Lord”.
Now this is interesting, her soul magnifies the Lord. Brings the Lord into view more clearly, brings the image of the Lord to us…
(To be continued)