This is supposed to be a trivially true statement, and yet it sounds controversial somehow, doesn't it?
The difference between the two is quantitative, not qualitative, unless you explicitly or implicitly subscribe to the "humans are the only real agents" idea, which is not even one step removed from "unlike other animals, humans possess souls". And yet when I browse through research on (embedded) agency, most of it is about humans, not anything less complicated. Sure, studying humans has an apparent advantage over studying other animals because we, as humans, have an inside view not readily accessible in other species. Whether it is a real advantage depends on how misleading the inside view is. After all, it comes with a dangling node of free will, with the feeling of qualia and ineffable redness of red, and with a host of other evolutionary artifacts that once may have been useful for survival in a small tribe, but now are a just along for the ride. And in any case, evolution satisfices for survival, it does not optimize the inside view for accuracy.
I understand why philosophy focuses almost exclusively on humans, but I don't understand why, say, AI research does not focus on simple creatures first, and maybe even on non-living agents before that. Well, that's not entirely true, posts like this one do appear:
but they seem to be a small minority, as far as I can tell. What am I missing here?