@curlykeetz Great, so that's where the new Sims 4 user data folder spawned. And that's where all your content needs to be.
Now go into Desktop > The Sims 4 > saves, pick one save file (it has to end in .save, not .save.verx), right-click, and select Copy. Then open a File Explorer window, double-click the C drive, select Users\your username\Documents\Electronic Arts\The Sims 4\saves, right-click in the empty space, and select Paste. Launch the game and let me know if the save you copied over also shows up.
@curlykeetz Great, so you can now copy over your other saves in the same way. Then you can move your mods and custom content from the folder you moved to the new one in Documents\Electronic Arts. Please do so in batches, testing each time, in case something is broken. If your saves don't show up or can't be loaded, you'll know there's something wrong with one of the files you just moved, and you'll need to split that batch and test until you find the problem file(s).
As long as you don't save your progress in your save games, you won't have to worry about missing objects. Everything will be back once all your cc is in place.