I definitely feel where you're coming from; complexity is certainly lacking, and this seems more like a proof of concept. The major way I plan to add complexity and variation will be with alternate "HyperCubes" (aka having different shapes that you view things through instead of just a cube), most of which won't actually be cubes. The Cube "world" will likely be the easiest/starting world. I think changing that will add quite a bit of variety, but it will make level creation a little less automated, which is why I haven't implemented it for this jam. I probably would've if I hadn't lost all my work and had to re-make it all 2/3rds of the way through the jam, but ultimately re-writing it from scratch really allowed me to address performance problems and optimize the whole thing which turned out to be worth it.
Anyway, thanks for the useful feedback! I'll be sure to take all your points into consideration as I continue development <3