You've done a really good job. The graphics, in spite of being pixelly, really capture the environment, with the cave, waterfalls, and scrolling mountain backgrounds. The sound effects are also good. I like that you focused less on music and more on keeping the purity of the background sounds. It kind of made the whole thing feel more organic. But when you do use music, it has a tribal fell, which is welcome.
What impresses me the most is how tight the controls are. No sliding around, running off ledges, and fighting to control some huge, looping jump. Good gameplay. My reviews often show that I get annoyed by faulty controls in a platformer. You want the challenge to come from the level design, not fighting to land a basic move.
As others have said, it's a pretty short and easy game, but that makes it no less fun. I think we'll see more complex games from you soon.
There may be a few glitches. Several times, I felt like I got hit with only one heart left a few times and didn't die.
Keep it up.