As others have said, not 'sticking' to the platforms made this a bit tricky and punishing for an opening level
You've got some z-fighting (overlapping cubes) as part of your background
The 'This door needs a key' text was off screen for me and then snapped to the middle
With the untextured platforms, camera angle and lighting it made it quite hard to judge the platforming - in the first level there's a platform that goes off screen a lot of the time!
it's cute, but could have probably benefited from some playtesting to help smooth out the difficulty curve!