I've felt that way before. My advice is to make a list of the things you don't like about yourself and then see how you can make them any better. For example, if you think you're ugly try taking better care of yourself. If you think you're stupid try to come up with reasons why you think you're stupid and things you can do to change that

You have a purpose. But we are not given the knowledge of just what our purpose is. Just let go and let the universe ( or God) guide your path.

These critters have a place here so I don't see why you shouldn't