My review (Sorry for my English, I'm a Spanish speaker and I use a translator).
This is my first jam as well. Greetings, fellow beginner.
There are only two levels, but they're good. It's a creative concept, and I really like the shield concept. It's very good. Perhaps some aesthetic details could be improved, like the font choice, which is Unity's default. Perhaps giving the player a smaller cooldown when shooting and giving the shield a cooldown could be elements that improve the gameplay, making it more balanced.
This is my full review (Don't forget to review my game too).