The game has good art and a decent music (death sound is very annoying though which kills audio a bit). The game is a bit annoying (an understatement actually) so I'll go with the assumption that you tried making a stupidly hard ragebait platformer. However there are some design decisions that could have been made to make the game feel better and the losses actually deserved.
First off there's the movement. You chose a snappy character controller but light taps on the arrow key sometimes translate to way too sudden and big movements, which makes the game feel unresponsive and is especially bad when the octopus is between 2 obstacles (and that happens a lot in the game)
Jump height isn't affected by how long you hold the up key, which is fine, but you can spam jumps by holding the up key, which would have been fine in other platformers, but not here because there's too many spikes everywhere across levels (look at the platform I circled in the image. Sometimes I'd jump off it to reach the next platform to the right, forgetting that I held the jump key so I'd then touch the spikes at the ceiling and start over. Not cool. Instead of that try an immediate key press approach with an input buffer).
Algae blend too much with the environment to be obstacles. Sometimes the player just forgets they're there. The shell things have a pointy end, and the pink purplish spiky things look very much like spikes. The algae don't look like danger at all so I died to them many times for no good reason.
And my complaints end here. I only completed 2 of those 5 levels and I don't think I'll be completing this today. Ragebait platformer did its job. At least it's a very nice looking game.