Without delving into the whole Ancient Astronaut theory, let's just think for a moment about UFO's. Unidentified Flying Objects. Flying machines and/or unknown animals, who for some reason beyond us, manage to evade our detection. I say 'evade detection' because at the rate in which 'supported' sightings seem to appear, you'd think the skies were teaming with UFO's. And yet, not everyone has noticed them.
For some reason or other, they can manage to travel through our skies, under our seas and from (possibly) planet to planet without a trace of evidence. But back in the 1800's they were a little careless.
The Airship sightings always consisted of an airship, some occupants who may or may not have spoken any number of European languages. Sometimes Russian. They looked like men. They had a knack for handing out baked goods (like the faeries of lore who also liked to hand out cookies or little cakes).
They weren't sneaking up on people in the night, and stealing them away. And if they were, no one was really talking about it. It was as if they took to kidnapping special people in Biblical times and then the 'taking' tapered off.
So it's safe to ASSUME the airship sightings don't come complete with abduction tales. Abductions begin to occur (again), much later. It's a giant jigsaw of schizophrenic alien endeavors. Which leads me to conclude more than one alien race is at work here, and they don't always check up on one another.
"Hey, Zeta Alpha, did you guys happen to abduct some life forms from earth in the passed, oh...I don't know...500 years?"
"Negative, Zeta Beta. We were just chillin' with the natives. They gave us peote. It was nice."
Whatever. Something about all of this is erratic. That is the best way to describe not only UFO's but the entire phenomena. Erratic. Which leads me to conclude there may be a dark agenda at hand. Oh sure, I could be exercising my right as an american to be paranoid. But...think about it...several different races, pulling tricks on humans, like the Trickster or worse, the Devil. The nice little encounters are miniscule compared to the freaky, outlandish, frightening and downright evil encounters.
Erratic, possibly. Ancient, maybe. Evil, definitely.