I really like the idea behind this! And I can see a lot of potential here! And I like how it slowly introduces new puzzle challenges too.
There are a couple of things that would improve this. Sound effects is an obvious one. But also limiting the camera so that it shows more of the level rather than being centered about the player character. (See the "limit" properties of the Camera2D node. I also have a helper pack where you can use a ReferenceRect to visually set the limit in the editor and not have to fiddle with figuring that out yourself. See the github repo https://github.com/jhlothamer/godot_helper_pack and the CameraLimiter2D node.) Since it's a puzzle game, players need to see the level in order for it to feel fair.
I'm sure there's stuff in my game that could be improved. I'd love to know what you think that would be! Please play and rate my game and let me know any thoughts you have in the comments! Thanks!