I agree with you. I'm pointing out that when 19th-century Christians on both sides of the slavery debate used the Bible to make their points, neither side had anything clear to go on. Christian abolitionists claimed that the overarching ethos of Jesus's ministry was incompatible with slavery. Christian supporters of slavery pointed to the fact that slavery was well accepted by Bible authors, including by authors who wrote after Jesus's lifetime.

In fact, modern opposition to slavery began with the spread of Enlightenment philosophy, not with Christian thinking or theology. Many people today don't know that or conveniently "forget" it, particularly on the political right, where conservative Christians often like to take credit for their "side" ending slavery.