Hey, thanks for trying out the game, and for the quality feedback! I 100% agree that a lot of improvements can be made. Good note on the invincibility frames. I think movement is more of a personal preference but I see your point - compared to other games with snappy movement this feels a bit sluggish.
I do want to release a sequel with more levels, weapons, enemy variants, and diverse biomes in the near future hopefully! I like the space genre a lot.