Nice little platformer. I like the sprite of the character and the idle animation. I also liked the dreamy sounding music. If you decide to expand on this, it’d be cool if you could add more visuals since the screen does feel empty. You might want to make the music a little louder, or lower the volume on the jumping.
I noticed you mention the game is meant to get harder as you get farther, but I found the entire game to be pretty easy. Nothing wrong with a game being easy, but thought I’d mention it since it seems you may have intended the game to be more difficult.
The game controls well, but I think the player moves a bit too fast. Maybe you could slow him down or maybe have some acceleration to balance things out.
Overall, nice job!