Your grandma had plenty of opportunities in the post war eras. During her time there was always a need for human workers. While I dont think AI can actually replace anyone reliably, I still can see how executives buy into this promise and try it. This is a unique situation humanity never was confronted with. Even the industrialization required a lot of human work. If all white collar jobs went away there is a huge imbalance in available workers vs available work. Simply adapting to this isn't a thing given that monopolies killed competition and its not feasible for your everyday Joe to break into markets anymore. Kudos to your grandma for making it this long, simply not a comparable situation however.

Survivorship bias

What you’re not counting is all of the millions of people who died because they couldn’t actually adapt to the new world

Which is fine but they didn’t need to be killed, they just became irrelevant and went away

So what are you going to do about it? You should probably do something then

And when did work done by humans stop existing between 1924 and 1990? Because that's the type of change we are talking about.

Well considering that she had a bunch of secretaries doing typing for her as a bank manager then transitioned to a world where there were no typists anymore was a pretty explicit change from her perspective.

She never learned how to type on a keyboard so you do the math

Well the math is that the amount of jobs done by humans in that period of time is above zero.

The math is: her job disappeared so she had to retire to a low income housing unit funded by HUD in Houston