Can you explain to me how a person with no memories and is born into a new world that is their first life for all intents and purposes qualifies as an isekai? You do realize 'AMNESIA' of any kind is a horrid trope that should be avoided at all costs? This is something a crappy soap Aptera writer does. Now you do it to lazy and not have to develop an m.c that makes sense? Did you just want a blank slate to make it easier? I can't understand why anyone would stoop so low as to do that..
Due to his soul being trapped in that void for so long he was bound to go crazy all alone and since he was focused on figuring out what those titles were supposed to be they latched on as the last bits of his former life.
The admin just took those bits and amplified them so he could enjoy his new life. He doesn't really care about not remembering his former life due to his souls care free style. I agree that amnesia is not the best troupes but all he forgot is his past life, he still has info of all of those shows and books he enjoyed.