I love the idea! I also like the simplistic art style, the character is also looks almost exactly like a character from a previous game I've made lol (Called 'OMLU', it even has the while/black versions).
The only criticisms are that the jump sound can get repetitive, just shifting it's pitch very slightly can go a long way. The other criticism I have is that I feel the timer is too long (At least on the first level), because after ~8 loops the starting area started to get overcrowded and I still had almost 2 minutes left on the timer.
Other than that I like the idea and the simple implementation!