I love this sort of reverse four-swords, solo-trine game concept! Having the characters also having their roles swapped is a great play on the theme, and the disorientation/disconnect it causes is testament to how clear the sprite work is! The game itself is also really solid for a jam entry and the enemies are badass.
That said, I think there's a few changes that would really benefit the game if you take it further (I hope you don't mind me getting into this)
Cycling through the abilities is a little clunky; you can't always bring the block up when you need it for example. You could tie your movement entirely to the mouse like (I think?) Diabalo (aim at the cursor, right click to walk) which would then leave your arrow/wasd keys available for your different abilities.
It might also be fun to have a way to cycle the swaps. Maybe the different characters' blocks are all better against different attacks (Sword could be strong against projectile, Fighter could parray?), or their range projectiles have different stats (the fighter throwing flaming qi-hadoukens, paladin launching vials of holywater....)
Anyway, sorry for the unsolicited advice. There could be something really good here and I would love to see y'all pursue it!