They’ve been here a long time... and we’re a unique life supporting planet. Not a comfortable combination.
I don’t believe the drone theory ... more likely they’re operating outside our understanding of physics. Maneuvers within a ‘tube’ - who knows? But if they were a danger we’d probably know by now.
There are ships log entries from the Columbus expidition that describe strange lights that emerged from the sea and shot off into the sky, or from the sky they disappeared into the waters of the Caribbean.