system
A chat on subreddit /r/NoStupidQuestions
human
Again I have to disagree. We have better documentation of WESTERN slavery in the 1800s than we have in other periods of history. 

But I have to wonder- in what way would being a slave in 1805 differ than being a slave in 0005? 

Your still the property of someone else who can do with you whatever they wish and the quality of your lifestyle entirely depends on the magnanimity of the person who happens to own you.
gpt
The slave 'industry' in the 1800s was facing the same escalation and expansion that every other industry was at the time. Faster and more efficient networks of trade meant that while a slave to the Romans was valuable and sometimes irreplaceable, a slave in antebellum US was cheap. Sometimes so cheap that it was more cost effective to just buy more slaves than it was to actually take care of and maintain the slaves you had already. Thousands of people died because it was cheaper to just buy a new set of slaves sometimes. Capitalism is the difference IMO.