I'm wondering, where are those stats from?
Also intelligence isn't just on/off. It's more of a spectrum with a gauss curve (this is why I.Q. is a quotient).
On the other hand I believe that most I.Q. tests are not deciding enough as there are too many various factors (and even people with issues like ADHD would've been wrongly called below the median).
And I'd even say that the Dunning-Kruger effect is apparently why incompetence and stupidity are in the higher ups since we always promote people until their incompetence.
On the other hand I'd like to hear what you mean about "mainstream propaganda".
Along with probably rats and cockroaches but then again being adapted to any situation and creating tools aren't the same kind of intelligence.
The numbers are a combo of normal distribution and polling results. They aren't exact numbers, as the results vary, but usually you get between those two numbers. And note that I said nothing about IQ, just intelligence; I'm considering practical use more than some test numbers.
IQ tests aren't very useful beyond a few purposes (like testing for intellectual disabilities). That's made even worse by the fact that we have 3 types of IQ tests: the ones that go up to 120 (based on the idea that it doesn't matter past that number), the ones that go up to 130 (which assume a little more points would matter, but that's a questionable hypothesis), and flat-out BS that goes beyond 130 (which are usually just internet survey junk and not real IQ tests).
The people who get promoted the most fall into 2 categories: nepo-brats who got mummy & daddy to just hand them the family corporation, and brats who got into elite universities because mummy & daddy had the money and influence to get them in, resulting in them making the connections to give the same result. Either way, power begets power, wealthy people almost always come from wealth (with the vast majority of the remainder coming from backgrounds of opportunity), and actual skill and intelligence aren't needed when you start off with enough millions in the bank that failure costs a fraction of a percent of what you already have. You can afford to be a super confident idiot when there's no risk in being such.
Media is, for all intents and purposes, a variant of propaganda. This is an inescapable fact of how it influences how we think. That doesn't mean it's all bad, though; just that it all works similarly. And mainstream media resembles the bad propaganda more and more as we've entered the age of tech-bro supremacy (although conventional bad actors are piggybacking on their corruption). More and more malicious actors are buying up mainstream sources, censoring out anything that doesn't fit the status quo (or says anything bad about, say, the CEO of a big online retail corporation). And all this is leading to a brain-dead media that makes it look like we've all become idiots when we're just losing our ability to have our voices be heard. And social media is no different and corrupting even faster, to the extent that we don't really have freedom of speech there, but an illusion of it that is skewed towards a bread-and-circuses situation that masks all the censorship (as well as personal data theft).
On that last point, roaches would die off if we didn't support them. They evolved with civilization to rely on us, and will die off if we go. Rats are similar, but will probably survive in much smaller numbers if our food supply gets cut off.