Well, for one thing, the concept of a human boy being raised by wolves in the exact way Mowgli was in 'The Jungle Book' is highly unlikely in real life. Also, the animals in the story having complex human - like relationships and conversations is purely fictional. The jungle depicted in the story also has a certain level of idealization and anthropomorphism that doesn't match the real - life jungle. So, all these aspects combined make it a fictional story.
There are several factors that show 'The Jungle Book' is not a real story. Firstly, the animals in the story possess human - like intelligence, language, and emotions, which is not how animals behave in reality. Secondly, the idea of a seamless coexistence between different predator - prey species as shown in the book doesn't happen in the wild. For example, in the real jungle, a tiger like Shere Khan would not have the kind of interactions with other animals that are portrayed in the story. Also, the way Mowgli is integrated into the jungle society with all the animals is more of a fictional construct rather than a real - life occurrence.
The talking animals make it not a real story. In real life, animals can't talk like humans as they do in 'The Jungle Book'.