I like the hand-drawn look a lot, and the rock music was a lot of fun (and something you don’t often see in a game jam!). The mapping was interesting too - I could tell you were trying to emulate four different musicians playing, rather than all one instrument, which made for some different rhythms than you often see in a game like this. (Although, halfway through all but one instrument dropped out lol)
I think the biggest issue is the controls. Usually games like this lay out the keys so they’re in a row matching their order in-game, and so that you can split the buttons between your two hands (look at something like Beatmania). Using the arrow keys both means that the buttons don’t line up with the tracks in-game, and also that you have to contort just one hand to press them all, which is very difficult. When all four tracks start playing completely different rhythms, I’m not even confident it would be possible with these controls - it’d be a hard map even normally! As is, it felt like getting tongue-tied in video game form, and I bounced off it pretty quick.
With some better controls, though, I think this could be a really charming little rhythm game! Making it about a band with characters could really add some life to the genre. I’d love to see what it’s like after you add the features you mentioned on your itch page, like story segments between songs and a more robust scoring system.