Hajime Isayama is a Japanese man with a Japanese education, and thus is using certain aspects of history and WWII aesthetics in his narrative. His main goal of creating Attack on Titan isn’t to push a certain political narrative (that may be an undertone he wants to convey, but if it is, I don’t think it’s extremely obvious who are supposed to be the Jews, who is supposed to be the Japanese, etc. Are the Marleyans the Jews? Or are the Eldians the Japanese? It’s all unclear). His goal is to *make money by courting controversy and be edgy. And its extremely edgy to flirt with fascist aesthetics in modern Japan. There are some troubling undertones to AOT, but I think they are product of the Japanese culture and upbringing of the author, not some kind of grand reactionary allegory.