50,000 years is a lot of time skips unless the story is really, really long!
Is the lead immortal?  Perhaps a god?  Telling a bunch of stories about a god trying to keep up with humans as technology advances could be fun.
Deity: What is this stuff?
Human: We call it 'writing'
Deity: Hrm.  So what else has changed in the last few thousand years?
Human: Err, I'm not sure.  I've only been alive for twenty years.
Deity:  Follow me then, by good friend, it's time for adventure!  You can write what I do with these 'letters', right?
Human: Yes.  I can, but I need clay, and a fire to harden it after.
And so on, every couple thousand years.  

((yes, I know people couldn't write 50k years ago.  Neanderthals were still around that long ago ))