Of course this may already have happened; remember Oumuamua the shard of interstellar rock that shot through the solar system at some 70,000 mph managing the extraordinarily unlikely coincidence of coming so close to the sun that it managed a pretty nifty slingshot around it:One option might be that what found Earth was a sophisticated probe – an AI, basically. I’m not sure how this would change things, except that it might be slightly more reasonable than a living being. Or slightly more relentless in its efforts to destroy all humans.
"Alternatively, a more exotic scenario is that ‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization."
Hmm, where did I put that old tin hat....