I really like the concept for this game and it looks amazing. It was clear when to switch characters based on the enemy weaknesses and the special ability where you have both characters out feels really powerful.
This is impressive, especially for your first jam!
If you decide to spend more time working on this game in the future, I think it would be cool if you added a way to upgrade your characters between waves. Randomized upgrades would make it a lot more fun in the long run!