The visual style and execution was nice overall! The concept / cinematic art was cool, but the pixel art in particular was excellent. There was some weirdness with the vertical parallax of the backgrounds when ascending and descending which didn't cohere with my sense of the change of perspective. But that might be my only visual critique. The main character sprite was especially good! I wanted to do more with him!
The music was also nice. I'd have preferred a more realist rendering of some of the music, given the centrality of music to the concept of the game... but that's just my personal taste. As for implementation, there were several times on the path between the two towns where the music changed from one cue to another and then back again in a way which felt rapid and arbitrary. Is it mapped to vertical positioning? I think it was mostly a thing when going up and down the huge hills. That could be tuned more smoothly. I especially liked the music of Brasswind Town.
Most of my praise is definitely centered on the music and visuals, because all the back-and-forth between the two towns (which are quite distant from one another) strained my patience quickly. I feel the towns are way, way too far apart, especially because there is not really anything to do between them. So, the pigeons of Woodwind Town have nabbed the dude's sheet music, and I need to haul out all the way to Brasswind Town to find twigs? There are trees in the background the entire way there, so I feel the fetch item should have been something that more logically justified the journey. And then, the person in Brasswind Town will give me a pack of twigs, but only if I find their cat which is "on the road just outside Brasswind Town" but actually it's almost all the way back to Woodwind Town. I will say, the platforming handled quite well, and again, the aesthetic experience of the journey was pleasant overall (the jump and ledge-grab animations are wonderful!) but it just feels like there's nothing to do between these two places except fall onto spikes. I was hoping there was some fun to be had in the caves, but it seemed there was nothing going down there either (although they did look nice).
All of that said, you should all be proud of what you've done. We do this to learn and grow, and it is a commendable effort overall! Clearly a lot of love was put into this. I think you have a very charming package, and the concept is cute enough, but it would benefit enormously from a reimagining of level design; in particular, probably a shorter and more intentional journey between the two towns, and a better reason to lead the player from one town to the next.

I was excited to try your game. I get an error when I try to load it (I'm using firefox).

I really like the retro pixel look