People who make these simple games are always talking themselves down after playing a game with more polish, but you really shouldn't
This game is genuinly loads of fun, I played 'till I managed to get myself a score of 123. Be proud of what you did achieve in stead of comparing yourself to others, you'll get there if you keep dedicated and make stuff you yourself enjoy!
If you want a small constructive criticism, and I hope you do cuz it's the best way to get better: A damage animation/character going red when hit makes it clear you made your shot/are in trouble, and could give a boost to the already great gameplay!