There is no reason the main character should be an adult from another world. He never questions why or how he came to be in another world. He never thinks about going back to his world. He never talks to anyone about being from another world. Even in his own mind he never brings up cliches like missing his smartphone or cheeseburgers. All of his friends are kids. All of his love interests are kids. All of his rivals are kids. He has the emotions of a kid. He has a child like innocence at times. The main character is just a normal kid from what we are shown of other kids in this world. Why not have him be from the world he is reincarnated into if they both have magic and he never mentions his old world? The author also relies heavily on you having previous knowledge of this genre to fill in a lot of gaps and being able to just jump straight to the over powered character stuff. Most of the story was carried by Travis Baldrees great narration.