Nab, you may need to read more history and read it more deeply. At the time of the Civil War, Republicans were the party of Hamiltonian activism while the Democrats were the Jeffersonian “small government” crowd. Somewhere in the late 18th and early 19th century, these positions flipped. I have not seen the reasons why. So by today’s standards, Lincoln would be a Democrat.
The whole thing about Democrats in the south is an artifact of the Civil War. They are Democrats because Lincoln was a Republican. The truth is their political sensibilities align much more with the Republican party. And of course they would have been opposed to anything having to do with Civil Rights regardless of which party proposed it. At least the Texas “Democrats” had the courage to admit their true party allegiance and switch to the Republican party.