I'd recommend reading the Main Nine levels, Level 11, Level 188, Level 3999, The End, The Frontrooms, the M.E.G., some of the Entities, the Kauer Thesis and the Theories
Tbh most videos out there arent even about this wiki, they are based on either just the general concept of "backrooms" or other wikis, so to learn about the whole lore and canon, you will have to disregard some of the things you've seen