Some of them are for sure. But it is an innate tendency for all of us? There is some new evidence that Neanderthals butchered and ate each other. Some older evidence that at least one factor in the extinction of Neanderthals is that modern humans killed them and ate them.
Animals in the wild use violence mainly in mating rituals and the aquisition and retention of food. Even then they seldom kill each other. Predators kill animals other than their own species for food. Most all animals firecely compete for mating rights. Even then aggressive displays are largely to win by bluffing. Humans and chimpanzees are the two exceptions to these general rules. Welll, you might count grizzly bears as another exception. Male grizzly bears will kill each other over access to a delectable food source, such as an elk carcass. It’s like one of them will own it only when the other no longer needs it. It’s unheard of for them to kill each other over the right to mate with a sow. Male humans, on the other hand, are quite famous for killing each other over a woman, as female humans are famous for killing a spouse or relative for an inheritance.
Humans kill each other for reasons that no other animal would think made any sense at all. Human hatred of other members of their species for political reasons is a trait no other animal has ever shown, to my knowledge at least. By “political” in this context I mean the aquistiion of power over other people. The pursuit of power is a unique human affliction. It is apparently, the utmost of all things that a human can attain for herself.
Hatred, power, money, sex and murder seem to travel together.