I made it to the level with the blue wall on the right and the red on the left but then got stuck, I could go through the blue, but not the red, and I couldn't figure out what to do, I remembered seeing the blue and red earlier, and I was able to get past after getting the shields, but I didn't actually grasp how they worked. Also the spinning level with the skip button, I got all the coins I think, and the door opened, but in the console it said that it couldn't load 'res://scenes/level3.tscn', so I pressed the skip button and that worked.
Overall I had a fun time playing! I liked the reverse movement mechanic.
And congratulations on your first game jam, and actually finishing something and submitting it! There is always room for improvements, but actually making something is how you get better and learn :)