Really cool concept. Was a bit hard to grasp at first because I didn't quite get why only 1 of the little guys returned to me, the checkpoints are a bit "overfrequent", so much that at first glance the return mechanic seems like it counts for all the guys.
But that's just a microscopic issue.
I really enjoyed the level design here. It varied quite a lot for the little amount of mechanics in there.
I am just a big fan of "big drop into a deep hole" levels. And the drop here was accompanied with the really neat orange guys.
Which in the end carry you a good ways back too. A neat hint towards getting to the Win screen. Also liked the 3 guys and the passage you could see early on in the level.
Completing it had a really cool feeling. Especially as I love those types of YOU WIN screens. Might be SMW nostalgia.
Some more tips for minor issues:
1. Took me a while to find out there's a loose animation. Maybe you should add a delay to the respawn input after getting hit.
2. The Air Ability of the blue guys confused me a bit. The wall slide looked like I could wall jump, but when I tried to do so it seemed like it was a glitched wall-jump. Maybe setting the abilities onto a secondary button, like c, would help a bit there.