You reminded me of why I don't like platformers...
but seriously, I loved the art, music, and sound effects! I was already making a game based on Mega Man Star Force, so it really hit home when I heard the 8-bit sounds <3 I love the typography and the splash screen.
There's a bug btw, on the first level with the ocean I think? When I died, I kept respawning 2x.
I got all the way to the boss fight, would love to see a more challenging one because I spammed E and won XD
Other than that, I love the double-jump mechanic, very creative! I love the way it just pauses in the air and once I got used to it, it was actually very helpful for the later levels. In fact, the normal jump was just causing problems when in tight spaces.
Awesome work!
edit: Also, you got the effects I wanted for the dialogs! I couldn't figure it out for my own game in time for the jam. I'm talking about the rainbow effect and the shaky font.