@pwalshwaring The next step here is to make sure Sims 4 is currently reading the correct folder:
https://sims4.crinrict.com/eng/2018/07/how-to-find-your-user-folder/
The game should follow the Windows setting, but it's always best to check before making that assumption.
If Sims 4 is reading the correct folder, you can put your saves and anything else you want to keep into that folder and pick up where you left off. You actually don't need to delete any of the other folders—the game won't get confused by their presence, and neither will Windows. I have a number of user folders on my computer, some inside Documents, some on the desktop, some that I put somewhere that I'm probably forgetting. It doesn't matter; there's only one location that Sims 4 reads, and only one folder in that location, so nothing ever gets confused. But if you'd like to do some cleanup, of course go right ahead.
@pwalshwaring Sorry for the late reply. No, it doesn't matter to the game itself if it keeps reading the Public folder going forward. As long as your content is all showing up, and OneDrive can't sync the files (which it can't if they're in Public), you should be fine.
I would definitely suggest keeping a backup copy of the Sims 4 user folder just in case though. Not that this particular setup is problematic, but you never know when a computer problem might surface and delete some of your data. And you never know when a Sims 4 bug might bork your saves for that matter. As an example, I periodically back up entire user folders (more for Sims 3 than 4) and put them on an external drive, then I delete the oldest when I know I won't need them. But if you don't have an external drive or USB stick, you could zip the folder and upload it to Google Drive or another free filesharing service.
And you're welcome. I'm glad we were able to work though this and get your game and your content working again.
