This was fun to play! I really liked how the projectiles bounced off the obstacles after destroying them. It really added another dimension to the game as I had to anticipate this, look ahead and plan what the best time was to shoot. I also liked how there were sometimes two possible routes through some parts of the game. You could make one mistake and drop to a lower level instead of instantly dying. The checkpoints were a nice touch of polish too.
Feedback:
I think it was possible to jump over the checkpoints and miss them, it would have been better if they were still triggered even if you jumped over them. Also some feedback when doing this would have been nice. ("Checkpoint reached" text flashing on the screen or something)
Also, at times the hitboxes felt a bit unfair: A common gamedev tip is to make the hitboxes a little smaller than the visible sprite. This makes the game feel fair as you can brush past enemies/spikes and still not die.
Good job overall and congrats on finishing and releasing your first game :)