@Randall the only way I can respond to your larger meta question is to consider the discussions of our current leading theorists and their preferred theories. Because the phenomena is so difficult to define I've long thought an interdisciplinary approach is the way to go. This is something we are only just starting to see unfold via the Archives of the Impossible new annual lecture series that are drawing experts and experiencers from various fields to contemplate the problem.
The one major consideration that you bring up is whether or not the phenomena have been with us all along, ever since human beings started to walk about on this planet. This implies long-term study or a source that is more terrestrial than extra terrestrial.
When you invoke the sociologist lens you move in a couple of directions - that of the folklorist and the evolution of a new religion. Vallee warned us of this in Messengers of Deception. We have a lot of constructed religions based on Ufology and even contactee, Whitley Strieber, supported the notion of an alien ship inside the comet just before the Heaven's Gate disaster. These are the dangers of belief before proof.

Pasulka has been been making the suggestion that long term manipulation of humanity can be seen in early Catholic documentation. if I remember correctly the location of where one of the European bilocating nuns appeared in America is also a well known supposed UFO crash site.
This kind of long term observation and contact suggests everything from being in charge of a control system to actual cultural manipulation on a much larger scale. Jesus was an alien etc.....There's certainly a lot of interesting evidence in this area to explore ,but I'm not a fan as I'm more Clark than Vallee.
And besides, the only thing we really can observe is the effects of UFO's on us and our culture as there's no real concrete evidence that they are the instigators of anything themselves. It's all human beings who start religions and make claims that they were abducted by aliens, and that's how one version of Islam was born in America.

What the folklorist has on their side is the fact that Passport to Magonia still makes a lot of sense, and even Clark agrees, and Cutchin has really magnified the point, that there is a folkloric continuity that currently takes the shape of aliens from outer space, as did the little people once upon a time, abducting us and taking us away to their magical realms.
There's something slightly tangible there as the phenomena is great at dressing itself in various costumes to suit the times, or witnesses simply can only report and describe experiences based on the cultural front loading and knowledge that they have.
That's why, there's only so much extrapolation we can make based on witness testimony. These are great stories, but we can't take it all on face value. they are simply describing things the best they can. In the 1800's a large object descends down from the sky and lands in a farmer's field. He says a door opened in this large oval and out drove a horseless carriage.
Anyways, I hope I haven't steered too far away from your question, but I am a firm believer in the word 'maybe', like you do Randall. I don't think we can judge intent at all. We still know next to nothing about the phenomena. Where, who, why and what are still all beyond us.
I don't see them conditioning us. I see us conditioning ourselves based on our response to these wonders in the sky. I invoke that title because the phenomena is definitely much older than the 1940's.
I was struck by philosopher, James Madden, during one of his many Plato's cave analogous discussions on the UFO Rabbit Hole podcast where he described the UFO phenomena as just a bit of a finger poking into our reality attached to something that we still can't grasp or begin to know.
