There is this concept of a technological singularity, Some days I feel it has already happened. And collectively we all are in a sort of tech time dilation, caught up in them, we barely notice the exponential tides.
I never thought about it in terms of being past the singularity event horizon, but the more I ponder on what you wrote, the more I feel you may be right: we're already experiencing what technological singularity feels from inside. We're riding the exponents already, but are still early enough that we don't notice.
(Or at least didn't notice. I thought progress of technology got boring in the past decade or two, but last couple years made me feel things are changing again, and faster than I can keep track of.)
I also don't think many of us can even undo mobile phones and the internet, so even going back half that far to 1970, even with unlimited money, it would no longer be possible to have the life we have today. To be always connected to everyone; to be unable to get lost; to always have more than most libraries at your fingertips, able to show you the step-by-step basics of any task you've never seen before at any time… it's a very different way of living.
I learned C and the basics of MacOS (classic) programming from books I took out of the library. I wasn't allowed to take out more than 4 at a time.
But when I think about trying to explain to someone from 1820, you can't explain anything. They were 40 years before Maxwell's Equations, so no electricity, no radio, no telegraph, no telephone. They were before the first common-carrier railroad. The first internal combustion powered automobile was 1808, but they were not yet practical in any sense. The precursors aren't there. (Yes, the industrial revolution is starting. The products of the industrial revolution that will change how we live aren't there yet, though.)
And just about everyone who speaks English as a first language can afford to use them - for leisurely travel.
"It's a sheet of glass, and moving pictures with sounds appear on it."
"How does it work?"
"I don't know. It involves several dozen separate inventions, of which I understand perhaps three individual ones well enough to discuss."
--
Of course, to really blow the minds of people from 1920, you can either show them anything related to space travel (especially the Apollo missions, but also GPS); or tell them about basically any organ transplant; or show them a 3D printer (you know Bakelite? We found better plastics, and we made a machine that can, without ongoing intervention, use that make any shaped structure we ask it to… and those machines can also do metal, and yes that includes the engines of those spaceships we showed you earlier. Also houses).
We are on a slow down. The first nuclear power plant was back in 1954. That's roughly 70 years ago. Except for tech/computers, not much has really happened in the world.
Medicine is radically better: some diseases eliminated entirely (smallpox), others reduced to manageable conditions (HIV), even novel pandemics get multiple vaccines within a few years; the first successful transplant was 1954, a kidney between two identical twins, because they didn't have a good way to do immunosuppression until 1970.
PV and batteries weren't impressive until suddenly each was a revolution.
Long-distance travel became cheap, widely accessible. My uncle moved to Australia (from the UK) to get away from his mum, my first trip abroad (aged, I think, 8) was to visit him.
Tech and computers enabled so many other things that I don't think it's reasonable to prefix them with an "except for". Even just going from 1954 to 2000 was approximately my Dad's career, and that included "we're sending you on a two day training course on this new thing called 'software'" (he worked for a UK defence contractor, writing simulation software for IFF radar systems).