So, here's my ambiguous answer: I think I'm real. Linda, James and Jack all really exist, but maybe not by those names. Everything is how I, Harry Culney see it.
I will say one thing is definitely fake: my last name isn't really "Culney". I changed it for anonymity's sake, plus (egotistically) so it would be easier to search for references to me in web search engines. If your last name is Smith, Jones, White, Black, or something else very common, it's hopeless to try to find yourself in infoseek et al.