Part of me sort of likes that you were initially confused when the first battle started as that fits very well thematically! However maybe there should be a short instructional message that first time just to clarify what the player is meant to do.
Yeah, variation in the environment and non-interactable props is something I really wanted to include but unfortunately ran out of time for. I note you don't mention the map. I do hope you were using it as otherwise you were definitely playing the game on hard mode!
Regarding clicking in the battles, there is indeed a cooldown as indicated by the cursor/crosshair animating and this is intentional design to limit the player's power as otherwise it becomes very trivial (and can also devolve into a pure dexterity game of who can click the fastest which I wanted to avoid). I don't think I would want to default allow the holding of the button to place blocks as I think you'd lose something with the less direct player input and no longer having a one click, one block relationship. It also runs the risk of being frustrating if blocks are placed unintentionally. However I guess something like that could be an accessibility option.
Thanks for playing!