I would say that Jhn does have a few stories written about him that seem to point to an actual person, be it in a somewhat different time.<quoted text>
Jesus is God and more powerfull then St John.
So he is a cruch to give the character jesus more veracity.
But how would you ever be able to reason that jesus is god?
Mind i'm not talking dogma now.
For your information, not even the entire church and related borrowed philosophies (Aristotle f.i.) have managed to do this convincingly.