I believe the statues were erected for multiple reasons. I think they were erected to show that the resolve of the South's population was intact and intended to persevere despite it's military surrendering and the entire landscape being in ashes and the way of life destroyed.
Another reason, I believe, was to THANK the military for fighting-off "the Yankee enemy" that posed a threat to their homes and their families- that thing that War really is for those who live in the wake of the battles. The Southerners were proud of those generals and soldiers.
But, those generals and those soldiers surrendered. They capitulated. And, they were literally fighting for the rich plantation-owning elite to continue to profit from the institution of slavery and that the white race was superior. I'm not embellishing when I say there was an instinctive belief that the white race was superior. I think history, since then, has proven that to be true. There are still a few that believe that. People like you and I don't subscribe to that same delusion, so we're not offended by the statues because we never think like that. We're also not black, so we never feel an affront because our great-great grandparents were treated as cattle. So, since we're in a unique situation, we have to make an effort to teach those who do think that whites are "better", that their ideology is not acceptable and no longer works. And, we show our black friends that we're empathetic to what they might experience.