>>There's a YouTube video about John Henry. He and his pre-teen son (John Junior) are wandering around looking for work, and they see a poster saying "Work On The Railroad".<<

Awesome.

>> he tells the boss that he had bee trained as a blacksmith, and that he earned his own freedom,<<

In fact, that is how a number of slaves earned their freedom. It was skilled labor, but white men often didn't want to work that hard, so a lot of blacksmiths were black.

>>Well, "John Henry, had a woman, her name was Polly-Ann, When John Henry fell sick and couldn't go to work, POlly drove steel like a man Lord Lord, Polly drove steel like a man."<<

I think I've heard that one.

>>And then there's the folk tale of Big Bad John. <<

Now that I haven't heard ...

>> Big john shoved the beam with his shoulder, and a miner cried out "THere's a light up above!" and twenty men scrambled from that worthlesss pit, but not John. They raised a marble stand in front of it,, which said "At the bottom of this mine lies a BIG BIG MAN - BIg JOhn <<

... but that's almost identical to what I wrote about Granny Whammy.

>>And she walks over to the cold dead corpse, and just gives him a great big New Orleans style kiss on the lips. And he gets warm <<

Well, that's New Orleans for you.

>>So John Henry was a black man with a mutation for super-strength, and his son carried it too, and eventually one of their descendants was Big Bad John...<<

Logical.

>> Now what was Polly-Ann's story? <<

I would guess, she had a subtler version of enhanced strength.

>> And who did John Henry Junior marry? Maybe there was a descendant named Cassius Clay? <<

Possible.