This kept me engaged quite a bit. I like that you designed the whole game around just using 1 or 2 of each element to solve the puzzle. The scope is very simple but engaging. I had a little bit of lag here and there but nothing major. Some of the instructions / popups were not acceptable by pressing space, whereas some of them were, that would be nice ux addition to always be able to use the keyboard to proceed. I didn't play all levels so i'm not sure if you had some of these, but maybe introducing ways to use a combination of eg. fire and a leaf to make some kind of combination of these for new puzzles.
I think the game as is has good potential already because the puzzles you can create are endless, but maybe some variety to the areas etc. would bring more juice. Overall very nice game.