By your own admission our society has always been relatively ignorant and under educated (I'm not sure I agree with that since we used to be number one in education in the world). Consequently there is nothing new that would change that other than just bringing the issue to the forefront now. There are just more instances now where they show their ignorance by grasping on to conspiracy theories etc.

Similarly the country has always been racist and we didn't know to what extent until trump surfaced. Now we know that at least 40% of the country is racist.

I very much disagree. The "dumbing down" began long before computers and social media were prevalent. The deliberate white-washing of history, the inclusion of religion in schools (especially in science classes), the war against teaching evolution in schools... these are all part of the root of the problem. Public education in the U.S. has been on the ropes for a very long time.

I'd agree that computers and social media have absolutely helped spread ignorance, lies, and misinformation, but they were not the initial cause of it.

Christianity has long fostered anti-intellectual attitudes along with their disparaging of scientists and evolution. Fox and social media have helped this dumbing down.

No. I think that that may contribute to the Dunning-Kruger effect, and may make ignorance more bold and visible, but it does not add to the sum total of it. I think that it really begins when those who control power and wealth, began to lose faith in education, as a generator of more power and wealth for themselves. In the nineteenth century, many with power and wealth thought that education was an unalloyed good, which would make for a more effective workforce, eager to buy more goods, which education would lead them to want.

But over the years it was realized that education in fact makes people self reliant, and teaches them discernment. So that those who had the wealth and power, began to doubt that earlier view, and especially they began to think that well educated people would have little interest in buying the goods and services they could easily produce. It would be harder to produce the goods demanded by those with discernment, and the fewer goods would reduce profits. The discerning and self reliant would not want to pay for shallow sermons on Sundays, junk food on weekdays, or canned entertainment on Saturdays. So that education (True education not just schooling.) became a low priority, for industry, church and government, since they thought that they could see, that too much of it was not in their best interests.