How do I backup files on my iPad to iCloud?

marjon988 wrote:

that’s my concern is they aren’t being backed up by iCloud.

Are you certain? Have you actually created a file, created a backup to iCloud, erased your iPad, restored your iCloud backup, and observed the file is absent?

Or, with less drama, have you considered using iCloud Drive?

Set up iCloud Drive - Apple Support

It automatically saves to icloud if you drag the files to the iCloud folder

You’re welcome.

Please realize iCloud Drive files are not explicitly backed up by the user - it’s on Apple to preserve them for you. But there is a “Recently Deleted” folder in case you accidentally delete a file and need to retrieve it (within a few days).

What does “Apple Documents” mean exactly? Where are these documents housed?

If they’re on your iPad, they’re backed up along with your iPadOS backup.

iCloud Drive files live in iCloud. They may or may not exist on your iPad. They don’t get backed up; however, there is a “Recently Deleted” folder (as shown in your screenshot) to hold mistakenly deleted files for a while.