Sentient means able to think, if I remember correctly, so all animals are sentient. To clarify, humans are of course just intelligent animals. Anyway, good question, it's true that we're similar to a complex computer, we're based on complex formulas. The difference is that ours is a chemical formula, while computers run on a mathemtical formula. This prevents them from going beyond the boundries of their programming. Humans...well I don't know what makes have opinions, what makes us think and desire to explain everything in the world. It's hard to put in words, and impossible to really understand.
