Nice simple game you have here, the sprites you've put together look pretty good, and the 3rd party assets youve chosen all fit in well. I did notice some of the pixel art looked a bit blurry, so it's possible the import settings aren't set up right in unity.
I realize you're probably new to game development, so great job on getting it all working properly, and setting up proper win/lose conditions, menus and everything. I will say however, that unfortunately since it's a 2D sidescrolling game with enemies only coming from one direction, the gameplay isn't really there, since all you need to do to win is mash the space bar for 5 minutes. I think this could be improved by letting the player jump and duck, and creating some higher flying and some shorter enemies so the player has to jump or duck to hit some of them. Also, placing the player closer to to the left side of the screen would work better for a setup like this, because it would allow them to see more ahead of them, to see enemies coming.
Anyways, great job getting something complete and playable, that's a huge achievement in itself!