So in 9x22 Metatron said “He’s in love… with humanity”
And in 9x23 Metatron said “I have to go deal with humanity”
He also wrote the story, so he knew he was going to deal with Dean.
So he was actually going to deal with Dean.
So that makes Dean = Humanity
So then the actual quote is “He’s in love… with Dean”
I think that’s as canon as it will get