Is "Salvation" by Langston Hughes a nonfictional work?

"Salvation," by Langston Hughes, is actually a short excerpt from his autobiography, The Big Sea. Autobiography is generally considered a genre of nonfiction; it discusses real people and claims to describe events accurately, in so far as the author can remember them. 
James Mercer Langston Hughes was born in 1902. The story recounted in "Salvation" takes place when Hughes was 12 years old. Thus, the setting can be dated to 1914. The Big Sea, from which "Salvation" was excerpted, was published in 1940, some 26 years after the events being described. One can then assume that Hughes may not have remembered every detail with perfect accuracy and may have used some of his skills as an imaginative writer to flesh out the details of the story. Although the story is basically nonfiction and we can assume it to be accurate in overall import, it is not a journalistic work (which would emphasize precision of detail) but rather an account of how the author remembers his early life.