Make sure you are not opening a duplicate.

• I have searched the issue tracker and did not find an issue describing my bug/feature.

Description of your suggestion.

The mod will not work. I tried everything to make it work, but it just will not. Apparently, you cannot drag-and-drop a .jar file directly to the available data packs. It needs to be in a or a .zip file. When I try to drag-and-drop a .jar file, I get an error saying "Non-pack entries - The following entries were not valid packs and were not copied: levelz-2.0.3.jar".

If it is supposed to be a .jar file, please make a tutorial on how to download, install, and use the mod in your worlds. It is hard to do it without a tutorial.

As @cedarisasigma already explained this is a mod, not a datapack.
If you want to use levelz you will need to use the mod loader fabric https://fabricmc.net/use/installer/.