Saint Augustine of Hippo (354-430) introduced the notion of original sin to the western half of the Christian Church, although it was never accepted in the Greek-speaking east and has been largely abandoned by many of the Protestant Churches. He said that original sin resulted directly from the disobedience of Adam and Eve, and believed that it could only be removed by baptism, so without baptism, souls could not go to heaven.
In more recent times, Christian Churches have modified their doctrine of original sin. Moreover, major denominations no longer regard Adam and Eve as literally the first two humans on earth, living just a few thousand years ago. Perhaps a little ahead of his Church's official position, Cardinal George Pell recently stated that the story of Adam and Eve is a myth, describing it as a religious story told for religious purposes. Without Adam and Eve, the doctrine of original sin will probably need to be abandoned or amended to remove reference to our mythical forbears.