Holme was a serf ——but he wasn't a serf from birth. During the time even earlier, he had been a miner in the mines.
Miner, and not slave laborer.
There were two types of people working in the mines — miners who had freedom and slave laborers who had no freedom. The former were freemen who willingly chose to "dig rocks" in the dangerous mines for the sake of bringing the bacon home, while the latter was the private property of the mine owners, equated to the tools and livestock in the mines. However, there weren't any differences between the two in some aspects —— they were all expendables that could die in the mines anytime, and no one would care to ask about them even after their deaths.
