Related to a Washington Post article along the same lines, I saw a meme that posed the question: “If someone from the 1950s suddenly appeared today, what would be the most difficult thing to explain to them about life today?“
I think it asks the wrong question. To be dumb is to denote less intelligence. Ignorant, lacking knowledge or understanding of a subject, may be a more appropriate term.
During my college years, my grandfather, a retired machinist in his 90s, could work through trigonometry and geometry problems with me using just a 5×8 index card. He knew his domain deeply, because he had no choice.
As a gen-x’r, I have had younger colleagues comment how much more I know than they do. There’s nothing wrong with them. We have become accustomed to the internet giving the answers, more specialization (know more about less), and a broader dependence on things (people, devices,..) other than ourselves. AI will further the dependence.
How would I explain 2020s life to someone 70 years prior?

I think I’d try to explain the internet, a global telephone system connecting everybody with everything. Highlight 70 years of continually accelerating technology development. Our ability to use a device that represents and epitomizes all of it, in our hand. And, for all of that, we suffer with information overload, as individuals we know less, and and are incredibly dependent–less self-reliant.. To the point many would struggle to even live, literally, without it.