Couldn't get a proper screenshot in fullscreen, so I thought I'd take this atleast
Either way, this is pretty cool for your first game jam. It's definitely a lot better than my first few game jam games lol. There were a few major issues I had with the game though
The player sprite really needed more animations, or atleast more noticabley different animations. The jump animation especially could've been a little different. It kinda made it hard to platform sometimes since it was a little too similar. As someone who can barely draw themselves, I get that art can be hard, especially in the constraints of a jam. You could animate the player through other ways such as squashing or stretching the sprite.
Also I'm not sure if this is a bug, but if you hold jump you basically continuously in place, or kinda do a quick jump off any ledge that's close enough. ( Could honestly be it's own feature with a little more polish though lol )
There were a number of times where the player was basically rendered behind the sprite next to them, like the treasure chests on the first floor, and some parts of the clock.
I also think the platforming section with the gears was actually pretty interesting, but it felt slightly janky with how you were supposed to climb them so to speak. Nothing necessarily wrong with it, but maybe it could've used a little more polish.
All in all, I'd say this was pretty cool for your first jam. Good going :)