My intent was not to discuss slavery as an issue but rather to discuss changing moral perceptions and how that impacts our views of issues.
However, agreed, Biblical slavery was different that abject or Roman slavery. However, the "kinder gentle slavery" of which you are referring to existed in law towards the Hebrews in general. It did not include foreign slaves who could be bought and kept as life long slaves and even inherited by the owner's children. But again, my intent was not to discuss slavery but moral perceptions and how that impacts our laws and voting habits.
Morality does not change just because time does.