Servicing and repairing many things in the house, but devices were far more easily diagnosed and repairable due to not being computerized. Really the “it’s broke and I gotta fix it” ability across age groups has really dried up. Doesn’t matter if it’s changing a tire on a car, or a kid having to fix a punctured tube on a bike tire to get to their friend’s house. They don’t ride anywhere for that matter. Changing brake pads. Changing the air filter in the home HVAC. People don’t do this stuff anymore.
Being bored.
Reading newspapers, books, magazines, etc. I don’t think people read as much anymore.
Hobbies. I think they’ve kinda died off, at least the physical ones. Model planes, trains, building stuff in your garage, cars, etc. Some of it’s been priced out of range or has gotten too technological for some, like cars, but manually creating something as a pastime has really disappeared.
Remembering a lot of phone numbers in your head.
I’m sure I’ll think of more, but it’s been a while since I was a kid and thought about pre-modern tech society.