Congrats on your first game!
Here's my constructive criticism. The falling rocks is a great way to justify the running, however the sound is too loud and we can't hear the music. Having different obstacles is good, but I think it would be more challenging if they were spaced randomly rather than evenly. I find the score in the middle of the screen distracting, but maybe that was the intent.
This being said, its a fully working game prototype with an animated character, a start menu, and a game over screen. You can be proud of yourself. Good job!