Rhythm games are something I've always wanted to try and make, but have no clue how to pull it off. You've done a pretty good job here!
The gameplay is fun, though fairly simple in execution. I was impressed at how each level introduced a new mechanic that adds something entirely new, but doesn't change the core gameplay and feels nature immediately. Well, mostly anyway.... I like the idea of the third level, but found it really hard to get a good flow going on that one. Pretty impressive nonetheless. (My level scores were C, C and F)
The music is great! I wish there were more SFX other than just the "missed-note" scratch. Maybe glimmers in sync with the music when you hit a note, a light bounce noise for the jumping. These were probably skipped to keep focus on the songs, but it felt like some extra audio feedback could help!
The graphics were also pretty good, especially Melody who is very cute! Much like the audio, I feel like just a few more elements could take this to the next level. Maybe a visualizer built into the level backgrounds that react to the music, or even some additional visual feedback when you bounce and hit notes.
Overall, this is a fun mashup that came together very well. Great work!