This is what tends to happen when it comes to humans:
God: "Be nice to each other"
Man: "But it can't be that simple!" and off they run to create a whole heap of rules, regulations, myths and legends to make something simple into something larger and more complex than it needs to be.
Where did you get the God bit from? This is how it tends to be...
Hominid species 1: Let's look out for our own little family unit
Hominid species 2: Let's help each other
Hominid species 1 becomes extinct
Hominid species 2 does not.
Hominid species 2: Helping each other is important, but we are too thick to understand why we FEEL it is important, therefore a big invisible man must have put that feeling there. So let's kill some animals, splash their blood all over the place, and cut off our sons' foreskins.
If I were a gambler, that's where MY money would go.