Any words or phrases are simply mental constructs to symbolize what humans perceive. That is the nature of language. Animal, in the context of this discussion, is a word to describe life forms which are not plants. A human is a particular species of animal. So is a fruit fly. So is a slug. So is an Amoeba. Is it immoral to experiment on fruit flies? If your answer is "no" then the moral line is somewhere between fruit flies and people.

Tomato plants are alive. Are they not living beings?