According to today’s standards most Americans were white supremacist’s in the 1860’s. Abolitionist who believed in equality between the races were a very small minority. However, there is a huge moral chasm between Abraham Lincoln’s views on slavery and the southern leaders views on slavery.
As far as your second point, and I can’t believe I’m saying this, I actually agree that it is shameful that the north, and the Republican Party, abandoned the freedmen to the tender mercies of southern whites. It would take over 100 years for blacks to finally be able to exercise their basic constitutional rights.
“. . . there is a huge moral chasm between Abraham Lincoln’s views on slavery and the southern leaders views on slavery.”
Southern leaders wanted the pro-slavery U.S. constitution enforced. Lincoln took an oath - twice in fact - to uphold the pro-slavery U.S. constitution.
Arguably, Lincoln took up arms to overthrow the U.S. constitution but he did pay lip service to it.
That's one reason I don't think voters are going to respond to any Republican strategies to Play the Race Card. It is a bad idea.
Trump's current strategy calling out the Dems about their real-time failures will work much better.