They were evil fucks. Slavery was one among many deplorable things conservatives supported and still mostly support to this day. They also opposed women's suffrage. They opposed civil rights and fought to maintain segregation. They fought against gay rights. They fight against trans rights. They literally fight against any minority who might land on an equal playing field. Hey... guess who has been stating lately that women shouldn't be allowed to vote?
They are always the first to cast someone as an "other" and scapegoat for all of their problems. You're the type of person to hear "Haitians are eating their cats and dogs!" or "Mexico is sending us rapists and murders" and say "That guy has a good point!". It's pretty fucking gross and you're a clown at best for defending them.
There has been a lot more than "some changes in alignment over the years"—the parties of 160+ years ago are essentially unrecognizable today. Given the nature of how the modern Republican party established its base over the course of the 20th century, this idea of taking pride in a legacy of ending slavery is basically comical, a fiction that falls apart with even a basic knowledge of the history of American political ideology and party alignment.
I don't think it is much more comical than modern Democrats trying to take credit for the civil rights movement. The Democratic alignment has changed from "judge by content of character, not color of skin" to thinking that practice is highly problematic.
1800s Republicans were a big business, religious, nationalist party. The Union side in the Civil War was motivated by religion (cc "Battle Hymn of the Republic") and nationalism. Rich men paid to have poor men serve in their stead.
They are always the first to cast someone as an "other" and scapegoat for all of their problems. You're the type of person to hear "Haitians are eating their cats and dogs!" or "Mexico is sending us rapists and murders" and say "That guy has a good point!". It's pretty fucking gross and you're a clown at best for defending them.