that depends on the people and culture, in more isolated, inland areas yes, slavery as a institution was often rather humane, often a way to pay debts or serve a sentence, and usualy temporary
however, in the regions where the hubs of the slavetrade were, where entire local cultures and economies were based on exporting humans, it was complete fucking hell on earth
and racism isnt applicable as a notion here, the slavers were often of one ethnicity or religion, the slaves were usualy any given 'others' or just their own surplus population or dissidents, that it was technicaly 'not racist' dosent mean they saw the slaves as anything other than cattle
thats one of the interesting parts about it, what does it say about a culture that it needs to invent a racial category to reduce humans to ''beasts of burden'' so it can justify slavery and mentaly cope with it, as opposed to a culture in which the notin of ''human cattle'' is just a completely normal thing that needs no special categorisation or justification whatsoever
in fact the forms of slavery that were practiced by english, french, portuguese etc, colonials from 15/1600 till abolition have that historicaly rather specific aspect that they chose to reduce slaves not merely to inferior status, non-person, or non-subject, but to a whole invented cathegory of ''non-human'', which slavery usualy dosent realy have, in ancient times the slave was seen as a animal, a non-person, but it was still completely taken fror granted that its still a human animal, in sex slavery obviously the victims are dehumanised and objectified, but its still a important point that theire human and the clients arent doing zoosex, in most forms of contemporary slavery the humanity of the slaves isnt even put in question in fact, obviously pigs and horses cant produce smartphones, make shoes, dig ore or weave carpets
