Ape Empathy Shatters Species Stereotypes

That's likely very true and makes sense.

It too seems likely that our violence towards one another also goes back that far. Take war for instance, even after the 'War to end all wars—WWI' and the utter horrors of WWII we're still killing one another on mass—take Ukraine, Palestine and Sudan for instance. Seems, we're very slow learners and or that we can't help ourselves.

Moreover, it's not just war per se—where contact with the enemy is often impersonal and sometimes not up close thus adversaries are essentially invisible at a personal level—but how vindictive and violent people can be in one-to-one contact. Leaving aside having to respond out of self-defense, many continue to deliberately torture and cause much unnecessary suffering to those they've overpowered, often the same happens with victims of crime. And some even take sadistic pleasure in acting so.

Despite many attempts over recent millennia to overcome this horrible side of human behavior it seems it's ingrained in human nature at a very deep level that goes back a long way in our evolutionary history. That's likely the reason it's been so hard to change such behavior.