As others have mentioned, there's a lot going on. I Think some additional UI to remind you which button is inventory etc. much like you did with the QWE attacks. Generally I'd say this is well polished. Dynamic music, solid menus and cards, moving backgrounds, but it does look like you ran out of time and had to use filler art. I saw the shop and was a bit confused why it just looked like a box. However, it's a game jam, so not a big deal when it comes down to things. I thought it would be worth mentioning that it broke my immersion for a moment though.
Like Atomion, I also started just spamming my attacks. I like the idea of the combo system, but I could never remember what those combos were. Maybe a key on the screen during battle, or even a system that shows the different combos you can create as you're typing them. For example, you might type WQ, and a graphic pops up with 3 options: WQWE WQQW WQEW, and as you type the ones that don't fit disappear.
Another combat related suggestion I have is to make the ! icons a bit bigger. I had some trouble noticing them, especially during the first boss fight. You might simply be able to scale them up, but maybe a small particle effect could help identify them visually.