This is incorrect.
I, as an author, created a world with laws, rules, places, and characters. I myself am not physically inside the book, which is a construct of my concepts.
I am not in a *particular, specific *sense inside the book. Yet, I am present throughout the book. Anyone who knows me will see echoes of me and my life and my thoughts inside the book, they will see the image of me in my characters, they will see my world-view in the course of events.
I am in my own story by my act of creation, even though I am not physically present in terms of place. Even in my own made-up story and world, each character can only be in one ‘place’ at a time, but I, the author, am everywhere in the book at once.
I can see the entire book from the outside, and enter the timeline when and where I choose, because I am not bound by the time and space represented in my story.
From the perspective of my characters, I am all-powerful and all-present. I can see the entire story all at once. I am not bound by its limitations except as I choose to be.
Now, upgrade the analogy to a truly all-powerful being, and maybe you can begin to grasp the concept.