[LearnsFromMistakes]

That may be the theological rationale you advance, but it isn't the rationale the Catholic Church uses.

I can barely represent my views, not going to try to represent the rationale the Catholic Church uses. I just wanted to point out the Immaculate Conception was an incredible solution to a theological problem. But later, thru science, the theological problem was non-existent. Jesus' blood could be a perfect/sinless sacrifice even if His mother wasn't sinless - He didn't have her blood in His body.

[Salvation]

Then from whom did Jesus become man?

The flesh came through the Blessed Virgin Mary. That’s why she was sinless — so that she could carry that flesh in her womb.