Pretty neat little platformer, I like the little details like the small intro animation that plays when starting a level & the diegetic level select screen. If I had to guess, I think you've also taken some moveset inspiration from The End Is Nigh? Ledgegrabbing is a movement option that's honestly a little underexplored in platformers, so I'm happy to see it here.
I think most people have already pointed this out, but the ledge snapping can a little too generous. I found myself often clinging to ledges when I was just trying to descend a bit, and controlling my jump height off a ledge felt a little bit too uncomfortable to try performing consistently (Though I did find the "hold down" mechanic halfway through writing this review, which is a good addition). I think maybe some tweaks to the overall movement & feel of the character could make this game really satisfying to master.
Also, for an "unfinished" level, I found the concept for the last level to be the most engaging one. I think the weird back-and-forth pattern was what kicked my brain into gear (pun) and started making me memorize the "boss patterns", per se - it becomes a fun game of trying to compartmentalize the entire sequence, trying to remember roughly where the clock hand would be at certain parts of the track (E.G. the hand will go to the top right at the bridge, it'll stay at the top when X instrument comes in, etc.) as opposed to simply memorizing a sequence of attacks & actions ala Super Meat Boy (You know that one boss I'm referring to).
I think the idea here is unique enough that it's worth fleshing out into a full title. I can already picture ideas like having a waltz move the clock hand in Forward-Back-Back triplets, or polyrhythms with the hour/minute hand that force you to keep track of 2 beats at the same time. Consider expanding this concept a bit more.

Also for the record I played this one because you submitted it on day 1 of the jam as "ITS-A GAME JAM-A TIME YAHOO" with a tiny super mario jpeg as the image and I'm glad you kept him in the description.