> At first, there were many people typing, then later [...]

There were more people typing than ever before? Look around you, we're all typing all day long.

I think they meant that there was a time when people’s jobs were:

1. either reading notes in shorthand, or reading something from a sheet that was already fully typed using a typewriter, or listening to recorded or live dictation

2. then typing that content out into a typewriter.

People were essentially human copying machines.