The church doesn't shy away from Peter's mistakes, he is generally held as an example a flawed human, called to something greater.

I dont know much about the origin of the Peter principle, but it was coined by a person with the name Peter,  according to google.

Interesting.  I suspected as much.  But given the Catholic church's influence over western culture, and given that they see the pope as a direct successor of Peter's apostolic authority, I'm a bit surprised that we're using this as a term.

SimpleStacker

It refers to the Apostle Peter being famously incompetent. He was supposed to be Jesus's right-hand man, and was "promoted" as such, yet when shit hit the fan, he's the guy who every remembers for denying Jesus.