But when and where have you seen this mindset arise in the past? Specifically the idea that the masses are ruled by myths, which explain how they got here and prescribe appropriate social behavior and that these myths are deliberately constructed by people who understand that this is what they are doing? Do we know of any religious or ruling classes from the past, which knowingly created culturally generative religious and secular myths to herd the great masses?

The closest thing I've seen to this isn't an actual historical civilization, but Frank Herbert's material for his Dune series, especially the Missionaria Protectiva as practiced by the Bene Gesserit: a solid chunk of Herbert's far-future setting involves the deliberate construction and manipulation of myths by those in power (or hoping to be in power), manipulating how people think and act via language - although Herbert calls the Bene Gesserit "witches" rather than wizards.

I'm not drawing this comparison idly: Herbert was deliberately drawing on concepts like Carl Jung's collective unconscious, Joseph Campbell's The Hero with a Thousand Faces, Marshall McLuhan's The Mechanical Bride, the Great Man theory of history, and the Sapir–Whorf hypothesis, and these are the same prototypical concepts that form the foundation of Adams' theory - the idea that humans are "moist robots" that respond to certain stimuli is characteristic of a line of thought which has more roots in science fiction than the historical record.

Which isn't to say that the power to influence people, through speech, writing, and action, and to consciously manipulate the public image of an individual hasn't been used historically - there are numerous examples of such activity. Egyptian monuments bearing the victories of the pharaoh (which might never have happened), Plato defined the "Noble Lie" in his Republic, Roman studies of rhetoric in public speaking, Napoleon crowning himself, the characterization of Elizabeth I of England as "The Virgin Queen" were effective examples of image control, etc. During the first half of the 20th century, many governments deliberately created, promoted, and distributed propoganda, and sometimes this took a very personal aspect to it, such as the contemporary cult of personality surrounding the ruling family of North Korea, which is intimately tied into the guiding philosophy of Juche. Some of these principles - like the "Big Lie" - were formalized in works like Mein Kampf.

This shouldn't be understood as Adams' being "correct" or that these are historical justifications of his "moist robot" idea. Many scholars have attempted to build models with which to help understand or predict human behavior; the step after that is trying to use those models in such a way as to engineer an outcome - that's much trickier than it sounds, and it requires thinking about people as "moist robots" that respond to certain stimuli in a certain way, without agency. That doesn't usually work in practice. A good example of it not working quite as expected is microeconomic theory: the conceit that customers are rational actors acting under perfect information isn't very realistic.

The tricky bit, however, is that rhetoric, propaganda, and media manipulation demonstrably do work to influence groups, even if, as William J. Groo said: "You can fool all the people part of the time, or you can fool some people all the time, but you cannot fool all people all the time." Studies in crowd manipulation and group psychology can yield valuable insights that can be used by savvy individuals to help sway a crowd or launch a successful ad campaign. Most politicians and governments don't need to fool everybody all of the time, so from a realpolitik perspective being able to fool enough people enough of the time is sufficient - which is why we have things like political ad campaigns. This is fundamentally different from Adams' "wizards" however - being a politician is an art, not a science, and the effects are usually far less than miraculous. Adams' presupposes that people are much more likely susceptible to influence because of their "programming", and that "Wizards" are far more adept at their manipulation, than they really are.

Do we know of any societies from the past where the understanding of the concept of a "noble lie" has been widespread in society? Where the great masses basically know that their social behavior is an agreed-upon social convention while giving lip service to it being dictated by some myth they understand to be false?

"Elephants in the room" like that are always very tricky to deal with; the reason social conventions are conventions is that people tend to accept them without questioning or needing justification for them, and it can be very difficult to establish whether people are even conscious of them. I think the closest you would get to it is the Victorian/Edwardian concept of pornography - /u/AnnalsPornographie would be better to weigh in on that.

If we subscribe to the idea that civilizations have natural life cycles, then would it be fair to describe that a society first starts out in a state where the majority believes the noble lie (what we experienced as "modernism"), then proceeds to understand it as a lie, but keeps behaving like it used to out of inertia (what we experienced as post-modernism), followed by... what?

Well, this is part of the thing where Adams' theories fall down: historians largely don't subscribe to that kind of idea today. The idea of civilizations working in cycles and "Big History" theories was really popular during the 19th century "Great Man" theory of history and early 20th century with works like Sprengler's The Decline of the West, but tend to fall apart under close analysis. You might want to read the answers about Postmodernism in Historiography from the FAQ, which talks a bit about that kind of thing.