I don’t know about all the old manuscripts, since I am no scholar. But I do know many of them were rejected, because it was determined they had been corrupted.
But you can take the story of the virgin birth to the bank. It was necessary for Christ to have been borne of a virgin, to eliminate inherited sin. Any corruption of flesh in his birth, (as the possibility of a human father), would have not resulted in the spotless perfect sacrifice Christ offered. If Christ had of been borne of a man, anyone could have sacrificed themselves for sin. But that would not provide the forgiveness of sins for the world; Christ made. The sins of the world are passed from generation to generation by our human fathers, because that is the way the blood line is passed on, not through the mother.
So it was necessary that Christ had to be conceived of the spirit, not the flesh. This is what made Christ the Son of God, not his baptism, crucifixion, or resurrection, but his divine conception.
