Solid demo! Regarding the player, fall speed is maybe just barely a bit too fast, and it would be nice to be able to move while aiming. Other than that, feels excellent to control.
The keys feel like something to collect and use in the level, rather than the exit. A warp vortex might be more inviting to jump into without fear of consequence, but obviously, this undermines the hub area. Perhaps you could bring the key to the goal warp and then use the ones you've collected to unlock special levels?
The last two puzzles were really satisfying to solve, Two 'aha!' moments, so to speak. The turnstile gates are a really fun mechanic and mesh nicely with the magnet. Great work!