@Cathode,
How do you understand the words of our Lord Jesus Christ, "none is good, save one, that is, God."? [Luke 18:19]
Do you see the context mate. Obviously there are good people, but their goodness is not their own, is the meaning.
They are not good of themselves, only God is Good of Himself. All Goodness comes from God.
So really it’s not a proof text that Mary was a sinner.
Mary had the indwelling of The Holy Spirit from her Conception, The Holy Spirit protected her from Original sin and all personal sin, so that she could conceive of her sinless flesh, the Son God.
Jesus was not “ implanted “ as a completely foreign alien being, otherwise he would not be in anyway human. Jesus received His humanity by being conceived of Mary’s sinless flesh, by the power of The Holy Spirit.
“ The Almighty has done great things for me “
“ I will put enmity between you and the woman, between your seed and her seed “
Adam and Eve became the seed of Satan by their sin and fall. Mary’s seed was Jesus, and it was her seed, since she knew no man.
Mary’s sinlessness made her an enemy of Satan, because from her could be conceived the sinless Saviour, she was under the Dominion of The Holy Spirit, not Satan.
In sin did David’s mother conceive him, but not so with Jesus, Jesus was not conceived of a sinful mother. Jesus was conceived of an Immaculate Mother, and He Himself was Immaculate and unblemished.
He was like us in every way, but without sin.