I think the blob needs more animation to feel more squishy and... well, animated. For example, he could stretch wide a bit on landing or stretch vertically on jump/fall. You gave him eyes, so there was a good opportunity to add funny facial expressions (tears upon death, closed eyes on landing, smug face when finishing a level).
Art in general needs more cohesiveness. The platforms, the enemies and the background look like they don't quite belong together. Back when I started with game jams, I was always out of time so I understand the polish isn't easy to achieve. I'd recommend starting with a minimalistic color palette (black and white only, for example) to find your style there.
You may find my review quite critical but hey, you still made a game in a week, which isn't something most people would be capable of. You should be proud of yourself. Keep learning, keep making games and you'll undoubtedly become better!