I'm thinking that space is not Lawless. This planet is ripe for the taking and yet we are still here. That to me implies that this planet is already owned and protected or that planets are not attacked willy-nilly. I would imagine traveling from one star to another you might need to stop and refuel. If the UFO sightings we've seen are from transient races crossing the Galaxy then we are a mear tourist stop.  Wouldn't surprise me if they grabbed a snack before they left. Or maybe stayed if they enjoyed the view. Probably some have been on this planet longer than we have.  My point is we are not alone and they're not as hostile as we've imagined. Cuz if they wanted us dead we'd be dead already.