The anthropologists twist themselves into knots to try and explain everything in the most non-violent manner possible.
And the primatologists were like that also until women like Jane Goodall lived amongst apes and reported back that they were quite violent.
Native Americans were hardly the peace-loving enviro utopians as some try to portray them. They were extremly violent towards each other as well. No particular knock on them, that’s just human nature deep in the genes - a fear of someone who isn’t part of your tribe, bred that way for good reason - because in the past, someone who wasn’t part of your tribe often represented a mortal threat.