Congratulations on the submission. I see some similarities on games like mario vs donkey kong, but more physics based
The level where there is a full grid of possibilities was a total turn off for me. The physics aspect is not very fun when you have to test, watch, fail, and retry with just a small increment of knowledge each time. It makes the puzzle feel more like work.
If you go the 'physics' route, you can make more open ended levels with more room for experimentation and remove the frustrations of having to retry and reset the level. Maybe you could automatically load the last setup and also allow to remove tiles from the world. You can also make the simulation a bit faster and add a shortcut to start the simulation, like pressing space (or maybe rerun the simulation automatically on loop, and the player can iterate on the level on the go? Kinda removing a 'fail state'. In this scenario, two or more characters could be simulated simultaneously with a small delay between them, but would not interact with each another, and the first one to get to the flag makes you succeed on the level)
Otherwise, you can go the 'puzzle' route, with more predictability and precise placement to succeed, like the first levels of the game. In this scenario, the game would feel more like mario vs donkey kong, where every spring makes the character jump the same height every time.
Mixing these 2 I think won't work. I was having fun until the last level
I hope this feedback helps the team :) good luck!