I don't know about the 'rejoice' bit. I think it is more about the worker being supplanted by technological progress - a stoic lament.

I'm guessing whoever originated the song started with 1801 simply because it scanned well,

Many people don't realize it, but pre-civil war, and post civil war, North Carolina was a major manufacturing state. Pre-civil war, it manufactured more goods than most, if not all, of the northeast states. Cotton mills, furniture, and leather goods, including shoes, harnesses, etc. were a big part of the picture.   I think it very likely the song originated in fairly near proximity to where it was collected. The economic history of NC and southern VA could easily have given arise to it, and it's sound and structure, and ease with the banjo suggest a southeast, rural industrial origin.

Janie