Thanks!
My goal is to teach the player how to play without written instructions, but it's difficult to view it from the perspective of a brand new player, so that feedback is very helpful!
I was afraid that a rewind feature might be necessary! I could imagine how to do it in a static world, but with enemies that move independently of the player I fear it may be beyond my ability.
Maybe it could be solved by allowing the player to pull blocks in addition to pushing, so they could undo their actions to some extent?