Humans have been eating animals for much longer than they’ve been working together with them.
While there is intelligence to animals it’s different from the type that humans have where they are able to adapt and overcome, leaving them near the top of the food chain.
The law of nature and natural selection is also part of what separates humans from animals. Humans evolved, becoming smarter, using that knowledge to become the dominant species on the planet.
With this grew civilizations, farming, and raising livestock. Crops alone couldn’t support an entire group of people, meaning meat was important to survival and people have seen no reason to change this. While the human body needs protein to survive people do not usually search out substitutes when they, like their ancestors, have meat.
It might seem unfair but for the world this is just tradition continuing on as humans continue to eat meat. Whether they’re raised for slaughter or hunted, in a dog eat dog world, humans got used to being the ones to eat.