I don’t know who needs to hear this, but not every fantasy or sci-fi story needs to be an allegory.
It’s okay to communicate the themes of your story in a more literal way. It’s okay to not even try to communicate some moral message or specific experience, and just use a story to communicate something more abstract like an emotion. It’s okay to just think to yourself “oh, wouldn’t this be messed up/funny/weird”, and then write it without trying to inject some greater meaning into it. Critics love allegories and symbolism because they’re so easy to intellectualize and tear into and discuss, but that is not the only valid thing to write about. This does NOT just apply to fanfiction.