I would look for sources of this in a conflict of interests. Most humans don't care about the fate of other species, as competition for resources is relatively rare. An exception is where animals can be turned into a resource to extract, with overgrown chickens as an example.

Whereas humans compete with other humans, and it's in one's interest to manipulate others to be less of competition, but more subservient instead. Even if the human who advocates for it doesn't benefit from it, their descendants will.

With conflicting interests at play, rational neutrality is hard to achieve.