Original sin... The bible states that Eve was the mother of all living. However, it doesn't state that Adam was the father of all living. I believe scripture shows us that the father of Cain is the serpent. And I think we were all created because God is bored or maybe lonely? However, making friends with a Robot wouldn't be as fulfilling as making friends with someone that could freely accept or reject you. Independently able to make choices resulting in death or life. Cain's lineage is never connected to Adam. Furthermore, you can see how Christ compared to the kingdom of heaven as a man sowing wheat, and his enemy came and sowed tares. Lest the harvest be ruined, the 'tares' (the weeds, the evil) are allowed to mature with the good (wheat) until the very end.