“...exhibit enormous cruelty to other animals”
You make it sound willfully cruel, beyond what is in their nature. One animal killing another is not necessarily cruel when in their nature to do so. Eating a prey animal while still alive may be cruel and terribly painful for the prey animal, however it is within the nature of the predator to do so as part of eating. Do you have examples that go beyond the nature of any given animal?
You can make the same case as “part of their nature” for humans.
A number of predators “play” with prey animals, if they are not hungry. Cats are the most common example.
For most of the history of mankind, it was common to torture captured men of enemy tribes, for entertainment.
Slavery was a step up.