Solid foundation for a top-down survival-style auto-shooter. All the core pieces are there, and the simple Unity shape sprites work well for the concept. Zooming the camera out a bit could improve visibility since progression relies on pickups and upgrades. A compass-style arrow at the screen edge pointing toward nearby or important pickups (like the Diamond of Doom) could be a nice addition. And of course, a kick-butt soundtrack to slay to would really seal the deal, lol.
Good job on your first game jam! This is my 2nd (first one was last week) so I commend you :)