What are we if not a system of sensors directing our muscles towards nutrients and reproduction
Your reductionist argument is as oversimplified as saying "Earth is just the cooled ejaculate of a supernova." True at some level, but only at a level without practical meaning for most purposes. It sounds cool and insightful. It isn't.
very simple organisms can't do that, at all. you really do need something with a lot of internal state and state-transition structure (ie, neurons) to do that.
Anyone who likes The Thought Emporium should watch his talk and branch out from there; you'll be amazed.