This is an interesting idea for a casual game, and for a first game jam I think it's a good submission! (I was also entering a game jam for the first time!).
I'd love to know how far you got in your test plays; I like to think I'm pretty good at platformers, but even on easy, it took me a few goes to get the first one completed (granted that's because I hadn't understood you were inside the 8 for a while, the in-game help could do with an update...!). But even after I understood that, the second is doable but the third feels tooooough. Typically games like this would reset the timer on a new 'level' (which is when you complete the number) like you have, but ALSO they'd make that time very difficult but then give you a little boost on collecting one of the pieces? That way, you're adjusting the time based on the number of items you need to 'collect', which feels fairer. Like if you set it at 20 secs to start but 5 secs on collection, you're giving 20 secs for a single collection, 25 for a collection of 2, 30 for a collection of 3 etc (assuming they complete it).
I think if you did that, you'd find it's a bit less feel-bad for players?
Also, you can't have a character called Clocky and then make him look like a battery...!?!