jeff the killer original story personal question

idk why, but this small part of the original story kinda bugs me a bit. At the beginning of the story, as everyone here knows, the boy who is attacked refers to Jeff the killer as a man. I personally feel like, for a child, it would be very easy to distinguish a man from a child, especially if you are a child yourself. This now begs the question. Are the events at the beginning of the story after a time jump, and Jeff is now an adult, or is this just shitty writing?