Thank you SO much for this incredibly detailed review! Yeah, Basement Dweller is something a lot of people are having problem with, but honestly I think from perspective of feedback, it's kind of a happy accident that it's like that? It helps us see what makes the other levels tick, and what makes BD less inutitive, so we can avoid the same mistakes when creating longer experiences in the future - the general consensus seems to be that BD should have been two levels, or in the very least, should have had a checkpoint in the middle (which is what we're planning to add to allow for longer levels without sacrificing enjoyability!)
We've also been going over solving the input system, currently considering either splitting the input, or using relative orientation between the camera and the selected face to determine if the block should be extrudable through mouse movement or player movement (looking at a block straight on makes movement controls more intuitive, but standing to the side of it does make it easier to use mouse controls
With the hub world we're planning to keep that structure, but greatly streamline it so that it feels less like a disjointed puzzle, and more like a proper "level select" screen akin to Quake's or even Talos Principle's - people just don't seem to like solving puzzles to get to the levels, which is entirely fair!