Loved it. Fun and simple. Background can be less obvious to keep the focus on the foreground / gameplay. The shots timing can be too long, so have a meaningful max timer (5-7 seconds max would be good). Include a jump meter - so the longer the player presses, the higher the jump - this would help the player in the continuous shots. Have patterns of shots, sometimes 1, sometimes 2, sometimes 5, etc... that would be interesting.
Finally, allow the player to jump anytime they want, but add a penalty there: if the player jumps but doesn't pass a projectile, then there's a penalty - for example, 3 times jumping without getting over a projectile they lose (lives counter).
Loved it. Really.