(As a student filmmaker) why am I getting depressed at seeing work that is so much better than mine?

First, it sounds like you are still new to the art. You may be expecting too much too soon from yourself. Does a college quarterback get discouraged and beat himself up when he sees a pro throw the ball? No. Instead, he is inspired by the pro. He watches and learns from him and continues to practice. Go easy on yourself and don't get discouraged. Most amateurs will produce amateurish type work. Stay with it and someday the amateurs will be admiring YOUR work.