No offense at all intended towards you James but aren’t you forgetting that for much of the Christian history of Europe and America, there was no such thing as “high school” or whatever the equivalent of “high school” was for the vast majority of people? Also, keep in mind that during the Dark and Middle Ages, school was something that only the rich attended.
Yes. We can certainly agree that education has changed greatly over the centuries both in it’s structure and in it’s availablility.
Of course - That still does not mean that people were unable to follow the mass. Those who could go to school studied Latin as part of their curriculum. Those who did not would still learn - at least - the responses in that mass just from hearing them from the time they were little.
I was born Pre-Vat II and before I ever even went to School I knew that when the Priest said, “Secula Seculorum”, the response was, “Et cum spiritu tuo”, and the priest would respond, “Oremus” (not sure of all the spellings here but you get the idea).
I even suspect that by the time I was 5 yo I knew what these things meant, at least in a general sense. How?? I asked. Children do that you know…

Then when I was in the 4th grade, right before the change to english, I was trained as an altar boy. I learned all of the necessary prayers, responses etc. from a card that had the prayers in three columns. Latin - Phonetic - English. My mother worked with me (and my two older brothers before me) until I had every prayer memorized. In fact I can STILL recite a bit of the old “Confiteor Deo” from memory. All of this I learned without ever taking Latin in School.
Unfortunately for me they up and changed the mass to English on me before I ever served a single mass.
My point is that, regardless of position or education level, everyone knew at least as much as they needed to know of the Latin since they had been hearing it from little on, and those who wished to, or needed to, know the mass better could generally do so.
With today’s level of education, and computer learning capabilites etc, there is no reason why anyone could not learn what they need to know to follow along in the Latin Mass.
In fact it is the children (the little sponges

) who will pick it up the quickest.
Peace
James