Proof of work was an idea, it is also in Bitcoin 's code, made up via code.
Make no mistake, Bitcoin has value because we agree it does. NOT because some guy or company spent energy mining it and securing it. Proof of work/mining help people feel good about using it. A more sound money helps people believe in it, and give it value. Nothing more.
Henry Ford suggested this a century ago. Using electricity markets and cost for a new monetary value system. It was around in other times as well. It isn't Bitcoin which created it or the idea.