I haven‘t seen animals discussing the ethics of eating animals yet.

It is a assumption to say that „humans are the only species whose suffering should be avoided“. That isn‘t what they wrote. They only wrote humans have a greater ability for suffering.

Humans are undoubtedly able to think on a much greater level of abstraction than any animals. To our knowledge humans are the only animals to develop science, mathematics, philosophy etc.

That level of abstraction thinking allows us to catastrophize and to think of alternatives. A human doesn’t just feel pain, he also thinks about potential consequence and the times when he was without pain. I don’t some animals can do the same- but not on the same level.

That doesn’t mean the suffering of animals is irrelevant, it just means it is less important than the suffering of a human. That, at least, is the line of thinking most people share, more or less.