It’s not as simple as the chattal slavery that dominates 100% of the discussion about slavery in the US. There were many types of slavery, some were temporary, some were even voluntary, some were merely about organizing labor, and some were far worse than death. Before industrialization, humans made the best livestock, so every sufficiently old culture has their own history with the development of slavery. Some started out as slavers, built on it and abandoned it, others never had it til their neighbors brought it to them, others tried it and self destructed. The same way every society had to come to terms with anything else that faced them, from their ecological stance, to economics, to militarism, all the typical external and internal factors of their time. You were not wrong, there are few cultures that have no experience with it.