Beyond violence, it's hard for people to contextualize how fragile life was prior to about 300 years ago - a scratch, some bad food, a broken finger, or any of a million tiny things that we just take for granted could kill you. Without an educational system, nobody knew anything except essentially what they gossiped about, learned from their trade or family, or picked up through direct experience. The world was a lot darker and scarier, and that made preemptive violence an effective cultural strategy. Things that reinforced tribal integrity and weakened other tribes, like violent traditions and religions, were effective memes for perpetuating lineages.
There are no humans alive who do not have horrific monsters for ancestors. We are alive and civilized because our ancestors did terrible, monstrous things.
It's wonderful that the dark, terrible things are the anomalies in this period of history, but we need to eliminate the notions of peaceful, paradaisical societies living in harmony with nature before the evil industrial revolution came along and ruined everything.
Humans are vicious, territorial, tribal, warlike animals with a nearly unbroken history of brutality, terror, and murder of outsiders. Our modern civilizations are marvels, even as deeply flawed and imperfect as we are.
It's important to honestly understand the good and the bad of our present situations, it helps us set the expectations for the trajectory of progress.
You could take a human baby from 200,000 years ago and raise them in a modern family in New York and they'd be perfectly adapted to these times. The corollary to that is a little darker - any one of us could have been raised in any of the savage societies thousands of years ago, and we'd have been just as brutal, ignorant, and murderous as any others.
The default assumption about anything before about 500 years ago should be that of a desperate fight for survival. The exceptions are few and far between vast and violent swathes of dead people.