Evolution of the Human Spirit

In trying to come to terms with the primitivism of Genesis, it occurs to me that its primitivism may be the point.  The Bible chronicles a history of humanity, hopefully the evolution of our kind.  Incest and shameless opportunism are atavistic traits, as are human sacrifice and miscegenation laws.  Jacob's dream of the angels going up and down ladders (Gen.28:12) suggest humanity's ascent and descent through the ages. 

Why Yahweh keeps telling these guys that all the families of the earth shall be blessed through their seed I don't know.  Is he simply saying that his seed will co-mingle with all of the families of the earth?  This doesn't seem to be so insomuch as there is a strong tendency against miscegenation throughout the biblical narrative.   Is he saying that they will be happy or prosperous?  Clearly not when you look at what happens to these people.  Maybe he is saying that the people of the earth will benefit as their lives will be improved through the efforts of his descendants.  Not that the descendants themselves will be happy or prosper, but that they will have this land and influence others in a positive way.  That seems a much more likely interpretation.  The descendants of Jacob/Israel will bless the families of the earth through tikkun olam -  תיקון עולם