Nice game you designed here. Reminds me a lot of Lowglow (https://store.steampowered.com/app/405950/Lowglow/)
I would suggest greatly shortening the tutorial, players get the hang of it really quick.
Also I would suggest making the items from the left bar draggable with one click without having to open a sub-pop-up-menu. This slows down the process of changing the layout.
Also I would recommend limiting the number of items you can place in a level. Otherwise there is no real challenge.