Well they don't have a human consiousness, as we can emprically tell. I personally think, and its just my thoughts, that animals expirence the world in a similar fashion to the way we do, this constant "movie" rolling before their eyes, they experience stimuli. The big difference is how they react on stimuli, how it seems they are unable to reflect on their own actions, stimuli-respons learning. They are organic robots or biological machines as you say, their consciousness is just their "OS" plants have a very different "OS", in that regard the capability of the human mind is what makes us different and gives us free will otherwise we are mostly biological machines by weight too. They are part of the envoirement that surrounds us and is just as valid a food as other living organisms. So why don't I treat them the same as a flower, because of the value they provide is different. Because of their physical features they can be easy to project emotions on too and empathize with.