This feels really nice, and it's the first sim type game I've seen this jam. Great job on the music, and the art fits the feel I think you were going for. The icons you see when selecting notes were great, they gave just about the right amount of information away ahead of the player committing to the action.
A lot of people seem to have suggested giving the game more direction, which I agree with. The ending is nice, and I found it quite intuitive to get to (just be increasing the amount of "things" on the island) but it was perhaps too simple. I think a minor change that could benefit the game would be something along the lines of random events, say bushfires you'd need to put out or an invasive species you'd need to kill off (although that one might be a bit against the tone). Just something small that would give more weight to the song choice the player makes at a given time. It's a jam game though, so I completely understand why that sort of thing isn't in this build but it might be a fun idea to toss around for any future versions.
Ultimately this game feels super unique, with excellent presentation, and an inspired take on the theme. There are a great amount of things you can do, and they fit nicely together with a good interplay between them. The gameplay feels really chilled out, and supports a consistent mellow tone. Well done to all involved :).