There’s a higher percentage of “things certain” than “things authentic”.
For example: Fiction vs Non-Fiction. There’s a lot more fiction in the world. Fiction is full of certainties, all depending how you view them. But they’re not authentic in that they’re not “real things”.
But non-fiction (which is also full of certainties) is also categorically (if not authentically) authentic and there’s far fewer non-fiction books out there
For example: You can be CERTAIN something happened in a fictional story. It says so in the text.
But was it an authentic event? No.