Was poverty really as rare in the past as Jason Hickel claims?

In response to the well known graph showing that the vast majority of humanity lived in extreme poverty in the recent past, Hickel has written an article purporting the opposite. He cites this paper by Robert Allen to back up his thesis.

Hickel then rounds it up by saying:

There’s a final observation from Allen’s paper that’s worth pointing out.  Allen finds that the $1.90/day (PPP) line is lower than the level of consumption of enslaved people in the United States in the 19th century. 

How correct is Hickel's thesis?