Well you know, God created Adam and Eve without sin.
Did it stop them from sinning?
Crickets. . . .
It didn’t.
Suppose He then ensured that Cain, Abel, and Seth (and all other children of Adam and Eve) were created without sin.
Would that have stopped Cain’s fratricide? No, it wouldn’t, because it has already been established that being created without sin does NOT ensure that the person so created might not choose to sin later.
That meaning the case, all humanity has been ‘weakened’, because ‘wiping out’ the sin of Adam and Eve would still not ensure that further humans would not sin. By the time you would get to Noah and the flood, you would have pretty much the same situation there was then, by that time just about everybody but infants had personal sin that was not repented except Noah and his family at the time of the Flood. They were saved. And yet, one of Noah’s sons after the flood himself chose to sin and was banished. So not even all those righteous enough to be saved from the Flood would keep from great sin.
Ok.
Separate issue.
God chose to send Jesus to be born of a woman.
Symbolically all through Scriptures, when God has been present, where He stands is holy ground. Where the Holy of Holies which represented Him was placed into the Ark of the Covenant, the Ark itself was made holy—so holy that a person could not even touch the ark, even to ‘protect’ it. That person would be killed.
Jesus would be fully, totally present as an infant in a human mother. To fully show the foreshadowed holiness of the Ark, Jesus’ mother, herself a New Ark, needed to be as absolutely holy.
Again, is this about humanity and ‘us’? No it is about Jesus. What is required of His Mother differs from what is required of us. He is a man like us “in all things but sin”, **including ** the heritage all other humans inherit from our mothers.
How is Mary different? She is, in fact, saved by Jesus Exactly like every other human being is who cooperates with God. We are all, every one, saved by Jesus, and ONLY by Jesus.
The difference is that Jesus saved Mary before her conception In order to fulfill all righteousness and to bring to fulfillment the great prophecy and testimony from the Old Testament.
It is all about Jesus and who He is.