you've got a ways to go, but it's not bad for a first time game, just pretty vanilla. I found that if i spammed the space bar as fast as i wanted, i could get as far as i wanted., until my wrist got tired. I made it pretty far, very easily. The hitbox for the ship seems to be kind of off, and the background in the 2nd level made it pretty tough to see the enemies until they were right in my face.
Maybe start the game off alittle more difficult, and add an upgrade system or something like that. shields, different weapons, ect. No enemy variety either.
Keep working on it though.