Y'know, I had an album of folk songs when I was a kid which included "John Henry", but I don't ever remember hearing that he was a black man. My parents wouldn't have mentioned it even if they knew, and it wasn't a song in any "around the campfire" group I was ever involved with, and the lyrics themselves don't give any cues if you don't already know that black men did most of the labor of building the railroads.

I do remember that the lyrics in a few of those songs had been severely bowdlerized. The chorus of "Sixteen Tons", for example, was:
"You load sixteen tons of number-nine coal,
I'm diggin' like a gopher down deep in the hole.
I'll be back tomorrow, you know what for --
To load that wagon with sixteen more."

I tell you what, the first time I heard the real lyrics (by which time I was old enough to understand what they meant) was a revelation.

I went looking on YouTube, but couldn't find any version of the song that sounds even remotely like the one I remember. I thought maybe it was by Tennessee Ernie Ford, but his version is way different.