So right now I'm reading through the Percy Jackson series. (We'll see how far I get into it. It's not bad, but it is way more derivative of Harry Potter than I had suspected, which has been distracting to me.)
What is most interesting is how so much of literature is based upon the same basic premise.
In Harry Potter, the hero realizes that there is actually a hidden world that we had heard hints of (magic); that there is a great, hidden power within that world (wizards and witches); that Harry is in fact a part of that world rather than ours (son of the Potters, enemies of the evil wizard Voldemort); and that upon recognizing this fact he has access to inborn gifts that he never knew he possessed.
In the Narnia series, the heroes realize that there is actually a hidden world that we had heard hints of (Narnia); that there is a great, hidden power within that world (the shallow magic of the Witch and the deep magic of Aslan); that they are in fact a part of that world rather than ours (prophesied ages ago to be the kings and queens of Narnia); and that upon recognizing this fact they have access to inborn gifts that they never knew they possessed.
You even see it with purely adult literature, such as the Odyssey series of Arthur C. Clarke. In it, we learn that space is filled with energy-based creatures who go about propogating life; that our hero (Dave Bowman) is selected to be the first member of the human race to join this group; and upon undergoing this transformation he can do things previously impossible.
Consider the Wizard of Oz. Alice in Wonderland. The Hobbit. Need I go on?
A huge portion of science fiction, fantasy, and children's literature is based upon this key premise: there is more to reality than what we know; we are a part of that world rather than ours; and through this connection we are much more important and powerful than we realize. Think through most fiction books, and you will find this to be the case - that there is more to the reality than we think; that we are a part of that world; and that through this connection do we gain our value as people.
Why do we all have this? Why is there this inner desire that so many authors and readers have found to be fascinating and inspiring?
I think it is an echo of Creation. We all know, deep down, that this world is not all there is - there is something more real out there. There is Someone pulling the strings. And it is through our relationship with this Someone that we truly gain our value, and we truly become important.