You say you know many descendants of coal miners, but apparently not any actual coal miners. So these people obviously opted not to follow the glorious path of their ancestors.
ML/NJ
I'd suggest you try it yourself before you pronounce how harmless the institution was. Have you even read any of the excerpts from Douglass's autobiography? And his experience was not even the 'ball and chain' existence that the majority of slaves experienced.
Imagine not having a clue who your father was, only having fleeting memories of your mother, and your entire life being able to be turned upside down or even ended on the whim or greed of another person know as your 'Master".
If you want to justify the actions of the Confederacy, try another track. Slavery was a horrible institution. You can't sugar coat it.
You say you know many descendants of coal miners, but apparently not any actual coal miners.
Within a five minute drive of my home are two, (now closed) coal mines. Within a 100 mile radius were the richest coal fields in America. I have know hundreds of miners from my very youngest days and I know of the battles they had in the past.
Those fortunate enough to still be working in the industry today are probably making more money than you and certainty well above the national average wage. They are not ignorant unskilled labor. They are very skilled equipment operators who happen to work in a profession that can be very hazardous. You would be damn lucky to even qualify for one of those jobs.