But that argument would only apply if Henry is Peter Pan (present tense.) The assumption is that he is not yet Peter Pan but he might become Peter Pan in the future. It would be as big a surprise to him as to us, since none of the characters (except possibly Rumple) seem to know exactly how time works between the worlds.
The only problem I have there is the circularity thing, that Henry already knows who Peter Pan is as a classic tale. At least, I presume he does, since they must have talked about Hook, and where the pirate ship came from. I guess I’ve handled circular time before in Sci-Fi stories but it does always make me a little 😕 .
Well, Emma already knew who Captain Hook was when she met him, so I assume Henry would too.