Actually Sumerian Myth #51 is indicative of the early origins of this silly Abel-Cain tale....except in the Sumerian version it is the farmer who comes out on top (because the Sumerians were mainly farmers not herders) and, oh. No one gets killed. The quarreling brothers are reconciled which is certainly a more civilized ending that this much later jewish horseshit.
https://books.google.com/books?id=77aDgC...51&f=false
https://books.google.com/books?id=77aDgC...51&f=false