In truth, Abu regained his memory within minutes of waking up, but in this unfamiliar environment, he dared not expose his origins and continued to pretend he had lost his memory.
Moreover, Abu didn't believe that these people would believe him if he told the truth.
He himself was from another world, and if it weren't for their ancestor's accidental gift from an Immortal, leaving behind a dimension-breaking symbol, even Abu would not believe that there were other worlds beyond his own.
Abu's family was quite influential in their world, but even so, they would not choose to reveal the existence of other worlds, or the symbols leading to them.
Abu thinks the people of this world are the same - the higher-ups are discreet about the existence of other worlds, and keeping it for themselves like a secret.
Who doesn't want more secrets under their control?