Plot twist - He didn't really transmigrate into a novel at all. The life he believes he lived was actually a delusion he created with his sister while he was in a coma after the accident. The trauma and his illness caused severe memory loss, making him confuse that imagined life with his real one. That's why he can't remember his past or recognize people from it. The top knows him from middle school, but because those memories were lost he doesn't remember him. He only feels a strange sense of familiarity without knowing why.
Plot twist - He didn't really transmigrate into a novel at all. The life he believes he lived was actually a delusion he created with his sister while he was in a coma after the accident. The trauma and his illness caused severe memory loss, making him confuse that imagined life with his real one. That's why he can't remember his past or recognize people from it. The top knows him from middle school, but because those memories were lost he doesn't remember him. He only feels a strange sense of familiarity without knowing why.