Well you gotta look at it from an anthropology point of view. Should a Shamatari kid be born and raised in New York, it would be as civilized as New Yorkers, that is grow to be a rude, aggressive asshole of course. Joking :)

These guys are situated in pre-bronze age level of civilization. By the advent of agriculture, society was probably too structured for these sort of primitive shenanigans to hold water much without the guy or the village being obliterated by the larger tribal community. Although I'm not entirely sure.

Reading the Bible and Greek mythology, it doesn't seem to be those guys spent much thought before resorting to murderous violence. If kings stole a woman (Helen of Troy) I would suspect it might have been occurring in the common population as well.

I'm not sure where the layer of civilization started imposing social norms but these Amazon tribes are (were) definitely preceding that.

There are literally no nations or cultures on earth that do not have this same affliction. We are all savages.

To consider otherwise is to take a step into racist, prejudiced territory.

This story displays the typical murderous human idiocy that you can also see in the history of major and minor royalty of the middle ages just happening in days not years and on the scale of dozens of humans not hundreds or thousands.