Why is Adventures of Huckleberry Finn an example of fiction

Huck Finn finds himself on wild and crazy episodic adventures throughout the book. Second, the novel can be considered a part of the bildungsroman genre that tells a coming of age story. Huck learns valuable life lessons through his adventures.

The events that occur are not recorded as true events, but as something that the author made up. Even though the events seem very easily possible, the exact happenings were a figment of the authors imagination.