The heresy is yours. You are spouting an old heresy called the Nestorian heresy. Re: https://www.christianity.com/wiki/christian-terms/the-nestorian-controversy-11629695.html
#2 Mary was a sinner, just like you and me. She needed the Blood of Jesus to cover her sins.
Catholics would agree but they hold to the doctrine of the Immaculate Conception. The doctrine of the Immaculate Conception is not supported in the Bible. Excerpt from: https://www.catholic.com/tract/immaculate-conception-and-assumption
Protestants’ chief reason for objecting to the Immaculate Conception and Mary's consequent sinlessness is that we are told that “all have sinned” (Rom. 3:23). Besides, they say, Mary said her “spirit rejoices in God my Savior” (Luke 1:47), and only a sinner needs a Savior. Let's take the second citation first. Mary, too, required a Savior. Like all other descendants of Adam, she was subject to the necessity of contracting original sin. But by a special intervention of God, undertaken at the instant she was conceived, she was preserved from the stain of original sin and its consequences. She was therefore redeemed by the grace of Christ, but in a special way—by anticipation.
#3 Mary's salvation is not connected to anyone else's salvation.
Many Protestants are not opposed to Believers on earth praying for and interceding for other Believers on earth. Catholics on earth believe that they can petition those in heaven and earth to pray and intercede for them.
Our nation is going to hell in a handbasket! Should Christians be fighting and arguing about Catholic theology surrounding the Mary, the Mother of God?
There is nonsuch thing as the Immaculate Conception.
Mary had human parents from whom she inherited a sin nature, just like everyone else on the planet who has a human father.
Mary didn’t need to be sinless either, because what you all claim God did for Mary in making her be born sinless from sinful human parents, God could have also done for Jesus being born of a sinful human mother.