If there is one generation every twenty years or so, then that would mean that going back just twenty thousand years — about to when the first anatomically modern homo-sapiens migrated from Africa into Eurasia and around the world — that would be a thousand generations ago.
Different kinds of hominins must have been talking to each other, vocally, in tribes — either modern humans or archaic humans, like homo-erectus — probably hundreds of thousands of years ago, or ten thousand generations ago. This could have been much longer though, some estimates say two million years ago, which sounds a little far fetched since the earliest known fires were only made a million years ago, or five thousand generations.
Letters, numbers, and various kinds of symbols had to be created in order to communicate with each other. The Bronze Age is when this started in history. The first written languages were the Sumerian and the ancient Egyptian hieroglyphs, which were about 3300 B.C. That’s 5317 years ago or 265 generations ago.
The first kinds of media, like photographs, film and video, for instance, weren’t taken until the mid-1800s. And I mean all forms of media — except literature, drawings, paintings, sculptures, and so on — were only invented two hundred years ago, tops. My earliest known descendant — my great, great, great, great, great grandfather was born in England 1747. He never saw a picture in his entire life.
All the way from when we invented language to when we invented pictures, music, and video starting in the early 19th century. Five, maybe six generations after that and we have had to evolve very fast adapting to what computers and editing can do to those forms of media we invented two centuries ago.