This was really fun! Honestly enjoyed it and I got to the "end," like what appears to be the end? Tried playing through again for secrets but couldn't find anything that changed the way it ended.
I did play through it twice though, so that tells you something about how interesting it is :)
Visually very appealing. There are some polish concerns with the UI in game (pause menu doesn't match the main menu aesthetic, death count is a bit prototype esc), but I totally let these pass on rating since it's a game jam. Oh, and the sword trail never stops even when you're just walking/not swinging. Again, not a major concern, just an observation.
Design wise, I would have appreciated check points when you get to a new area based on having to die to get there, like a checkpoint for after the first double jump for instance. Some of the repetition after dying seems unnecessary when starting from the very first point. What you did do here which I like is that enemies don't respawn when you die.
Sound: largely good, just missing a sound effect for when you land/become grounded after a jump. Sometimes I jumped too soon, thinking I had already landed, but wound up double jumping instead and thought it was a regular jump, so I died not being able to do the next jump which I meant to use my double jump for. Hope that makes sense.
Level progress: I like the sound effect and visuals for moving the islands, but I didn't always know where to look so if I missed them moving sometimes it took me a while of panning the screen to find where to go.
All in all, a fun game and the concerns/critiques above are just objective critiques I'd give to any game that was made in a normal amount of time. Please consider this game a serious success! I enjoyed it, and I'm sure others do too.