Actually, "war," as it is usually thought of, did not come about until a few thousand years ago. For the millions of years that "humans" lived before that, conflict was solved peacefully, as it is most often done to day, or occasionally violently. In the case of the latter, it was merely one, maybe two, people kill one other person.
That is hardly warfare. Feuding didn't come about until later, as hunter-gathers have no clan system of family lines with which to group one clan against another, so all conflicts were personally, one on one, or one and his brother on one.
What I call warfare is two or more political organizations who fighter each other. That means that the goal can not be the death of any individuals, but rather of a number of the other group,
Also, those people of the pacific islands weren't true hunter gathers when Europeans met them. Rather, they were Chiefdom.
Due to a natural surplus of food, fish, they were able to be come sedentary and develop “advanced” social systems, including chiefs, nobles, warriors, peasants and slave.
It should also be noted that there are numerous hunter-gathering societies were they truly are peaceful. Some of them, despite having poisonous arrows, intentionally did not fight against slave traders; but instead would most often flee when they came.
While some “primitive” societies do have brutality, not all do, most don't. While some exploit natural resources, most do not.
On a final note, there were no tribes of large families, only bands, which people went into and left to live with other bands often, and close relatives. Everyone in a region was distantly related to one another, and few had stronger ties to anyone more than anyone else.