I like the idea of a simple, straightforward game because, personally, for this type of jam, I prefer games that could realistically run on an actual Nokia 3310 rather than just a 2D game scaled down to 84x48. That said, the execution has a few weak spots you should look into, and hopefully you can address them in your next jam:
First off, the visuals flicker heavily whenever there is movement, most likely due to a downscaling shader applied over textures that aren't scaled by integer multiples, which ends up looking quite jarring. As for the gameplay, the obstacle hitboxes are way too large, and I constantly found myself dying on jumps that visually seemed fine. I’d also suggest adding some visual feedback upon dying to improve clarity.
All that being said, it’s a complete game, and I truly appreciate the effort that goes into delivering a finished project, as that's never easy.