One of the best games of the jam for sure.
The art, sfx and music are wonderful. The animations of the bird are really cute too! Well done on that.
The main mechanic is unique and pretty challenging at times. It has a lot of potential! I get the idea of the checkpoints being on the previous level so you can backtrack easily but it can be a little frustrating mainly because of the strange feature (maybe bug?) after hitting a wall. Unfortunately you have no control while falling and you can't save yourself after a mistake of hitting a wall. I think that if you apply some tuning on that the game will be more skill-rewarding and will be a completely different experience.
I really hope you will keep developing this gem. I will take a look on your others game for sure. Great great submission!