All the hats are showing in creative mode but I can't equip any of them

1.20, downloaded "simplehats-forge-1.20-0.2.0.jar", can upload logs in a bit. Basically-- I can see every hat but they are useless, I cant do anything with them

What game version? What mod version? Fabric or Forge? Upload your latest.log file from the logs folder.

1.20.0 is outdated and unsupported, update to either 1.20.1 or 1.20.4.
Curios updated and broke compat, the 1.20.1 and 1.20.4 versions have fixes for this.

if i update will i lose my builds though

Make a backup of your world then update and see, 1.20.0 worlds should be fine updating to 1.20.1.
You can look up guides for updating your game.