cool looking visuals, but veeeery boring gameplay
and also the creature switching mechanic is flawed since it drags the playtime quite a bit
That's fair, honestly. When you spend so long getting the basic framework in place, you're left without the time/energy to implement some fun puzzles.
The backtracking is an issue, yes. One idea I had since the deadline was to add vents that you can unblock as you progress, so catching the other creatures up is as simple as finding the nearest vent and quick-travelling to wherever you want to be.