I have finally discovered that it is perfectly acceptable to discard my original opening to a story. Who cares? I can always keep it in a separate file if I don't want to lose it.
The chances are that your first opening paragraph is tentative, feeling its way into a story that doesn't exist yet. It may not capture the essence or mood of the main characters or guide the reader into their world. It may contain too much scene-setting, when those details should come naturally, scattered throughout the main body of the piece. It should be stunning, thrilling, maybe comic or even tragic, possibly a question or an exclamation. But whatever it is like, it should pose enough mystery and spice to draw the reader in.
Sometimes I think my stories don't 'get going' until the second or third paragraph. So I like to remove the opener and let the story begin at a more exciting moment, right in the thick of the action. Hence the fruit bat vomit. Explanations can come later. Engaging the reader can't.
So let your fruit bats fly freely.