ok but could be better

Yeah, what SkyFire said. Movement feels very odd.

The controls are, I would say... unpleasant? I mean, you press a movement key and the character quickly jolts into the movement direction, as if he is lightweight and quick whereas when running you release the movement key, but the character still continues to run and then slides quite a long distance, as if he is heavy and ha a lot of inertia, and those two things are inconsistent with each other.
This also means that you have really bad air control, which makes it hard to land on enemies.

The art is really pretty, though.

I also think the game could benefit from background music, a story and checkpoints or lives, so that you don't restart the level each time you make a mistake.

The first level is fine, some simple platforming to start, but the second feels a bit unfair, especially on hard difficulty, here the enemies act now as platforms and i don't see it necessary, since if you manage to get to a high part and one of those enemies hits you, you have no way to get back where you were. The controls can feel a bit uncomfortable, it makes you walk more than you should.
Something i found cool was that wall jump that you can do in the secret area in the first level, i couldn't do that on the rest of the game (except for a part where there was a box), maybe you could implement that move on the main moveset, it could offer many possibilites for level design.
Overall, it's not a bad game, it just needs a little bit of work on the last levels, they need a more interesting level design.

I swear I've seen this sprite and game somewhere from a big pixel artist on youtube. Regardless if you're him or not, I found it cruel that enemies don't respawn. You miss a jump, you're done. The hitboxes felt weird at times, especially at the secondary level with the powerup climbing up the crows.

The health bar is rarely an issue. It's a jump-quest.