Lol you know, if we are talking about slave labor in a high magic fantasy world humans are probably a fairly poor option in the first place.
The system would probably be similar to the slave system in classical greece. Where the slaves were all actually government property and were just loaned or rented out to citizens for thier use. Having more money the government would probably have skeletons (they are quick, work all day and all night without ever having to eat or be closely overseen), constructs for heavy labor or gaurds (not golems, but there are lots of other cheaper constructs), and creatures like ogres or hill giants (captured young, liberally charmed or dominated) for big jobs that require more brains then a construct has. Even for jobs that require human like beings goblins would be way better. They are weak and cowardly so you dont have to worry about revolts much. They have as much intelligence as people, are smaller so probably eat less. And they breed like rabbits and have a faster life cycle. So the slave population could more easily be self sustaining and likely even grow. The quick life cycle would also have more of them born into slavery. Creatures who have never tasted freedom are less likely to fight for it. Plus if you compare them to wild goblins the slaves life actually looks better in some ways. I mean even a dirt floor hut and small rations are better then sleeping in a nasty cave, being hunted by everything in creation and probably starving to death on a regular basis.
Why would anyone choose all the hassle of human slaves in a world with goblins? Except maybe for concubines. Which is a fairly limited field and in many fantasy settings the impression given is that elves are more attractive. So even for pleasure slaves the elven races are a more likely option.
The system would probably be similar to the slave system in classical greece. Where the slaves were all actually government property and were just loaned or rented out to citizens for thier use. Having more money the government would probably have skeletons (they are quick, work all day and all night without ever having to eat or be closely overseen), constructs for heavy labor or gaurds (not golems, but there are lots of other cheaper constructs), and creatures like ogres or hill giants (captured young, liberally charmed or dominated) for big jobs that require more brains then a construct has. Even for jobs that require human like beings goblins would be way better. They are weak and cowardly so you dont have to worry about revolts much. They have as much intelligence as people, are smaller so probably eat less. And they breed like rabbits and have a faster life cycle. So the slave population could more easily be self sustaining and likely even grow. The quick life cycle would also have more of them born into slavery. Creatures who have never tasted freedom are less likely to fight for it. Plus if you compare them to wild goblins the slaves life actually looks better in some ways. I mean even a dirt floor hut and small rations are better then sleeping in a nasty cave, being hunted by everything in creation and probably starving to death on a regular basis.
Why would anyone choose all the hassle of human slaves in a world with goblins? Except maybe for concubines. Which is a fairly limited field and in many fantasy settings the impression given is that elves are more attractive. So even for pleasure slaves the elven races are a more likely option.