It would seem that the **BIG DEAL **is that if Mary isn’t a person like Eve prior to the fall then the resulting Christ isn’t God/man. Christ would have original sin and obviously not God/man. To avoid this such a Christ would need to possess the body of man, like evil spirits possess men, which makes the validity of His sacrifice questionable. Man would be left doubting who died for our sins, God or man? And, we know that the two natures of the Second Person in the Trinity are inseparable. God can’t die, so the only logical result is for this kind of Christ to be a man. As a consequence, with such a god, we would be right to ask if human sacrifice appeases God? There are other equally objectionable heretical conclusions contrary to Christ’s teachings.
These heresies were raised in the first 600 years of the Church all from the same source of questioning the virginity of Mary. The only Christological formula that produces God/man is for Jesus Christ to be born of a New Eve. Mary is the human mother of God who is blessed with original justice at birth (a creation of God), which is partly restored in us at Baptism.
There are posts in this thread that address this - maybe you missed them.
JoeT