Besides the other blogs posts where I explain that Catholics exalt(not worship)Mary because God exalted her first a few words to non Catholics. When you ask the question why do you worship Mary that's called begging the question. It's like asking, why do you get drunk to someone who doesn't drink.
We don't worship Mary.
Jesus is true God and true man.Human and Divine.
Mary is human.PERIOD.We are greatly devoted to Mary because God chose her to be the mother of Jesus. We call her our mother because she is truly the mother of all the living. We call her our Mother because Jesus is her son and OUR brother. We call her Our Mother because Jesus gave her to us to BE our Mother. I also know that because Jesus is God that He would preserve His own mother from all stain of sin.I also know from Genesis that God put enmity between her and Satan.It would have to be total enmity,nothing less. I also know that the Angel addressed her as FULL of grace,hence no sin. Jesus saved her by His death on the cross and she brought our redemption into the world through obedience to God,submitting her will to His.Yes,Jesus saved her and did so from the moment of her conception. Just as He died for all sins,before they were even committed.Time and space mean nothing to God so to speak. He's not restricted by our calender and our clocks.God is outside of time and space. We can say Jesus entered history through a woman.
And a great portent appeared in heaven, a woman clothed with the sun, with the moon under her feet, and on her head a crown of twelve stars.
She brought forth a male child, one who is to rule all the nations with a rod of iron, but her child was caught up to God and to his throne [Rev. 12:1, 5].
Highly recommend Jimmy Akin and his exegesis of the verse from The Book of Revelation