Hey DangoSama, let me give you a bit of the feedback that I hope will be useful for your design :) I think you could make the game easily longer and more fun/understandable for players if you introduced mechanics one by one. You have three mechanics in the game so far: spikes, pressure plates and hammer that destroys boxes/shows levers. What you could do to make this game way more appealing is to create separate, similar rooms in which you introduced all of them one by one instead of throwing them all at player at once.
So first, you start with empty room with just spikes - player goes through it, notices that spikes are a danger here, "alright, I gotta beware of spikes!".
Then, you put a single pressure plate in the middle - player presses it and door opens.
Then, you put two or three of them and player needs to figure out the order of pressing.
Then, you add a lever. Then, a hammer and a lever.
This way, you can make the game longer with assets you have already but teach the player through the gameplay itself.
Also, the pressure plates should have audio cues that tell player whether he does it in a good or bad order (it's a very simple trick to teach people how to do stuff).
I hope this was helpful!