Footfall nails this. Aliens show up and drop rocks on us from orbit. The reason we prevail is the only plot I’ve read that makes sense.
How To Beat Aliens
They didn’t invent the ships or tech they’re riding in and aren’t much, if at all, more advanced than us. Plus, we figure out their rigid social hierarchy and turn it on them. Also, we nuked Kansas.
NW Florida, very conservative. Saw one in Taco Bell a month ago. Before that it had been a couple of years.