That question is endlessly fascinating to me. Story has been called "the way we explain the world to ourselves" and "the way we explain ourselves to ourselves." Story is a waking dream in which we reframe our lives in symbol and metaphor to find meaning.
Story is an entertainment, for the one spinning the story and for the audience.
Story is a learning tool and a teaching tool.
As in all writing, story is an attempt to communicate, to create an effect: laughter, tears, anger, awareness ... or a willingness to keep reading to the end of the story.
All that and more. Exactly what story is and how a story ought to be structured is a topic constantly evolving and always in debate. Some of my stories fit the standard criteria for "the short story form" in creative writing classes: many don't. They range from serious to completely giddy. You may like some of them and dislike others. I've worked to make them express what I intended, communicate it, and be as effective as workshopping could make them -- but not everybody is going to like everything.
Which is good, because if everybody liked the same thing all of you would eat up all the chocolate in the world and not leave any for me.