As someone who made their first puzzle game semi-successfully, I can say that I really, really enjoyed the concept here. The design is just elegant, what can I say?
I would make it more clear how the "combined force" push works when breaking more complex shapes apart. It's something I can see players missing but being able to ignore in the simpler application of it in the final level (which would become frustrating should you make more levels which depend on the mechanic, for example).
Yeah, simple shapes, sound design, and mechanics, but nice and very modular depth (my brain couldn't help but smile when I saw that I had to trap myself in that U-shaped one to get past it). I would play more of this - shoot it my way if you want some more feedback on future levels!