the majority of people were barely educated at all
Correct.
Literacy levels alone bear that out.
Certainly.
The quality of education for those who had access to it was very mixed
Here's where I don't agree.
I look at mathematics work produced by 8th graders then.
I see how people wrote in middle school.
I see that 20 year olds who were in graduate or doctorate programs would blow 90% of the current professorial class out of the water.
The much greater selectivity, led to actually deserving people receiving education, and it yielded much more impressive results.
So... I misspoke when generalizing to such a wide extent, but what I had meant was that educated people back then were more educated than educated people now.
If reviewing the actual policy makers, the top military commanders, parliamentarians, and officer class - you'll see that they put to shame any Ivy League or Oxbridge guy from nowadays.
To pretend they were some kind of medieval brutes is nonsense.