That quote from the Lincoln-Douglas debates has become ubiquitous of late: neo-Confederates use it prove the Civil War had nothing to do with slavery, while anti-racists use it to show Lincoln was just another white supremacist & not the "Great Emancipator". Neither take into account that as a politician Lincoln often told his audience what it needed to hear, & in Illinois at the time free blacks were not allowed to vote.
Lincoln didn't become an abolitionist while president. He always was one. E.g. in an 1854 speech in Peoria, IL: " I hate it [slavery] because of the monstrous injustice of slavery itself. I hate it because it deprives our republican example of its just influence in the world -- enables the enemies of free institutions, with plausibility, to taunt us as hypocrites...."
Nor would I call the Emancipation Proclamation his saving grace, not when he caused passage of the 13 amendment, banning all slavery in the US, through a very divided House of Representatives. I think that was his lasting contribution to emancipation.
Ironically, many anti-racists today hold Lincoln to task for favoring colonization of free blacks—an experiment which was tried on Ile A'vache near Haiti & failed disastrously—while at the same time declaring that racism is in the "DNA" of the US. While I believe Lincoln abandoned colonization ultimately, he also foresaw the difficulty of integrating nearly four million people who were ethnically distinct into the society that had held them in chattel slavery for generations. What example did he have to go by but the book of Genesis during which the Israelites got out of Egypt so fast they didn't even wait for the breads to rise!
And didn't the younger Adams argue for nine hours before the Supreme Court on behalf of the Amistad rebels?
Otherwise, your points are well-taken, we live in the country founded by men who owned other men & didn't care to grant equal rights to their women. One cause of tension between the colonists & the Crown which is seldom taught in US schools was the formers' desire to settle west of the Allegheny Mountains on land ceded by treaty to those Native tribes & nations that had fought as allies of the British during the Seven Years War.
It was, as you point out, complicated.
