This is a common piece of misinformation. While the parties have changed over time, republicans have transitionally always been representative of natural rights and on the right, while democrats were more focused on egalitarianism and other more left-wing topics. Freeing slaves was a republican policy because it was focused on natural rights, the civil rights act takes natural rights while producing a more egalitarian society (i.e. to ensure everyone is allowed in your water fountain I must require it through law, and close your store if you refuse). Certainly the parties have shifted over 200 years, but I don't think you're fully caught up on your history.

That said, this article is about removing references to slavery in national parks, so I'm not sure where your point is going.

During the days of slavery, the Dems were the party pushing to maintain the status quo and the existing power structure. The Republicans were those fighting to change it.

Coming out of the civil rights movement, it was the democrats who wanted to change the status quo and the Republicans who wanted to defend it.

In the present period of endless culture war and polticization of everything, it seems that the democrats are the ones on the side of the status quo and existing power structures. They want to shove everyone into identity groups, put those groups into hierarchies, they want to shame certain groups and grant new privileges to others.

A lot of people are exhausted by the culture war, tired of having every aspect of our lives coopted to remind us to feel bad about ourselves and to hate each other. I don't think Trump is really offering a new path here yet, but he's recognizing what people say all the time in private and which the democrats refuse to accept.