Gawd. Hitler comparisons are never helpful.
Hitler is a proxy for evil incarnate. His example allows folks to turn history into a Manichean struggle. It rarely is. Usually, things are much more complicated.
It seems to me that the central theme of the civil war was about whether the Southern States were entitled to leave the Union. My own sense is that they should have been permitted to do so. So from this perspective, I think they were correct.
But there was another matter in play as well. And we focus on that. The vast majority of both Republicans and Democrats nowadays think the Confederate cause was wrong over slavery.
That's another useful message which statues can relate. History is messy.