Given the fact that Jesus was fully man, I’d submit that there are exceptions to this rule.
mary, being the Mother of Jesus could just as well have been an exception to this as well.
The Bible isn’t a stranger to setting out a broad truth about mankind and then offering examples that break the rule.
Romans says that there is no man who does good, no not one. But the book of Acts calls Barnabas a good man.
The trick is in understanding how the Bible portrays man and God’s sovereignty.
He is indeed sinful, fallen, broken, as says traditional Christianity generally, and Catholic dogma specifically. But that’s far off from Calvinistic ideologies of total depravity where all mankind is desperately wicked and can’t do good to save his life.
Man is fallen, but God is and has always been in the business of making saints out of sinners. Some are saved earlier in their lives, others backslide and have moments of weakness, but God preserves them.
The fact that God would choose one human woman, Mary, to preserve entirely from sin from her earliest moments, doesn’t contradict at all his truth that without his special grace, she would have been sinful, fallen, and broken too.