It seems to me that attributing negative “human traits” such as violence, greed, or guile to animals is acceptable because it serves to disown the worst of our human selves and project it onto non-humans. This is reflected in our language all the time: when people act out of violence, greed, or stupidity, we say they’re behaving “like animals.” We don’t say they’re behaving like humans.
By the same token, we deny animals the positive attributes we reserve only for humans because if we conceded that they are like us, we would have to reconsider what we do to them, how we use them, how we abuse them, and that we systematically kill millions of them on a daily basis. Conceding that we, too, are animals would threaten the superior, dominionist position we have established and work so hard to maintain. And for that, billions of non-human animals are suffering in every corner of the world."