" "Like I said, Democrats thought black people were not fully human"
Back when they were conservatives "
False. By conceding to the lie, you're perpetuating the lie.
I was surrounded by old school Democrats when I was child, raised by them. And being from 'the old country, they were REAL Conservatives, with REAL conservatives values, not these poseurs who adopted the designation because of desegregation but, as seen from their other habits, are anything BUT conservative. Ever hook up with any of them, spend a night at the bar with? Them folks are UN-straight laced to the point of scary. I know people who moved down South or even just vacationed there - kink don't even cover it. Heck, even from rural PA which ain't in the South, my gosh, they make us cityfolk look downright, well, conservative. Folks don't say our "Catholic girls start way too late" because they're Billy Joel fans. See if you can find informal polls by Rock stars back in the 1970s on how they rated groupies acrosss the USA. The only place they claimed that outranked the South in terms of the wildest chicks was - get this - Utah. YUP, U-T-A-H - the most 'conservative' state in America.
See, what we're talking about is reactionaries. Yes, they want to conserve segregation and the illusion that their women are dutifully subservient baby producers, but just because they plucked 2 items off the list don't make them anymore conservative than Che was Cuban or Lee Harvey Oswald was a Soviet or the Sex Pistols were geniune Punk Rock instead of manufactured pablum.
The Northern Democrats differed from their Southern counterparts because they were counterparts in name only.
Look at the map. An entire CENTURY before this faux 'switch,' the schism was already there. There was never a switch in party stance as a whole, just in membership when the entirety of the DNC united against segegation (save for the short-lived Dixiecrat Party which cleaved off in 1948 just to fizzle out), and the GOP of the South STAYED racist and took them in and flexed their hate-biceps.
Granted, there must have been at least SOME 'White' Southerners who were anti-segregationists, and in due time and such I'm sure someone will actually identify all 4 or 5 of them, but, well, need I continue till we see some photos of 'White' marchers with "STOP JIM CROW NOW!" placards down in Alabama PRIOR to them getting bused in from up North in the 60s by - yes, Democrats?
tl;dr: The difference was regional, not party.