Has anything messed with sResourceArchiveList or Llst2 in the ini file? If there's nothing there, then the meshes can't be found. I think MO may dynamically adjust these, and so NMM may have also started doing so.
Of course the bsa files themselves could be missing, but I'd expect a message for that. An empty list may make the game think there's nothing to load.
Try deleting the mesh files located at: {SteamLibrary}\steamapps\common\Skyrim Special Edition\Data
Meshes0.bsa and Meshes1.bsa. Steam will redownload them.
You can also try verifying the game cache.
https://support.steampowered.com/kb_article.php?ref=2037-QEUH-3335
The lists look good. And stick with Wrye Bash, it will always work better than the others.
Something strange: I tried to launch the game in Windowed Mod (in the options), and this time it loaded the mesh (characters, carriage, etc). However, the background far away trees and sky seemed to move in opposite direction than all the rest (for example, if I turned my head to the right, the trees and sky would move to the left, it wouldn't stay locked on the ground)
Also, the "besthesda presents - Skyrim" and the menu wouldn't be locked in front of the camera. Hard to explain, but for example, if I turned to the right, the menu would stay at it's original position, and leave the screen by the left (this is very weird). When I hit escape, I had to roate 180 degrees to have the menu in front of me, it felt like a VR menu (completely bugged tho.)
Still unplayable, but it means the game can load the meshes, somehow.
Also, it is probably nothing, but when I launch the game, the sound on the Bethesda logo (th "TUM... TUTUM") is a bit broken in the middle, always. Except when I laucnh in windowed mod. Don't know if that is a symptom of a related problem.
All in all, it seems quite fu*ked up, and I have no idea in which direction to go to make it better :/
Stick to whatever manager you like the most. At the moment I like the built in one from bethesda.net.
Maybe it will help us more if you run a dxdiag.exe and post the full report in spoiler tags.