Shan is considered to be a first person narrator because he both tells the story and appears in it.
A first-person narrator would obviously use the first person pronoun (I) to refer to him/herself. So, the entire story is told from this person's point of view, using that particular pronoun. E.g. 'I saw him standing there...' is an example of a first person narration which Shan is an example of. If he were talking about someone else, it would be third-person narration.
Guy de Maupassant's work are deemed naturalistic because his characters are usually the working class and they are often portrayed in a very harsh conditions of real life where misery is prevalent.
Majority of his themes are about war and German occupation. His stories focus more on women, especially those who are victims and prostitutes. A lot of his stories also focus of depression, paranoia, and madness usually resulting to death and destruction.
Yesterday's basketball victory - the crowd was ecstatic - guarantees us a chance at the state title.