I agree this is the real problem: to actually define what it is we mean by consciousness. I also agree that consciousness needs to be addressed as something that inheres most likely in all living things. An adequate theory should explain how human consciousness is of a kind with the rest. As you say we mostly just know more about our own kind for the obvious reason; it shouldn’t be a standard for any and all manifestations of consciousness. It should definitely be a natural account. But we can’t approach it as a thing we can isolate. Consciousness that is equated with something simpler actually would be about something different.