Many American Conservatives today see Abraham Lincoln as part of their legacy and blame the Democrats for the Ku Klux Klan and Jim Crow, however progressives conversely claim this is a fallacy and state that back then the Republican Party was the progressive part and the Democratic Party was the conservative party. Which claim do you believe is closer to the truth, as far as i can see both parties were pretty conservative by today's standards with the Republicans being the party of big business and the Democrats being the party of the southern planter class. It is probably a mistake projecting today's politics to the past but I would like to hear any thoughts.
You're right, projecting today's politics onto the past is a mistake.
Here's the thing: What Liberalism means evolves with time, not only in relation to society (always moving more a more liberated society) but in relation to other political movements.
If you consider the Democratic Republicans-Democrats one continuum of American politics, and the Federalists-Whigs-Republicans as another continuum, you'll see that, by our modern standards, they're all over the map.
Throughout the 19th century, the Democrats were always the more populist of the two sides, moving for increased liberalization of the political processes, examplified by the triumph of Jacksonian Democracy. On the other hand, they also were firmly tied to the regressive institutions of the south, both ante- and post- bellum. Meanwhile, the Republicans were generally pushing for increased centraliziation and plutocracy, but also, in fits and spurts, racial equality.
Saying one was more liberal or more conservative than the other, by our standards, ends up with you chasing your tail around as you go. Then, you have both party's strong flirtations with progressivism, an entirely different dynamic of political reform, as the 19th century gave way to the 20th. Just to make things more complicated.