Thank you so much for the feedback and kind words, I really appreciate it!
I also agree to your points - this is a demo/prototype and some of the features and choices in it are not final, but demonstrative. In terms of submitting the game in time for the jam, I ran out of time to do more music and get the notes to drop in sync - the final game will indeed have different songs (the whole point will be to collect them) with varying levels of challenge as you progress! There's also going to be additional elements in the rhythm battles, where, in the final game, it will actually be possible to fail them. There are also going to be some 'relationship' mechanics with your bandmates, which will make the more challenging battles later in the game a little bit easier.