Unfortunately, many seem to have just decided, then and now, that they are all inherently bad people beyond enlightenment.
To your argument: How do statues of racists and slavers in their communities, schools and courthouses serve to enlighten these people?
A better question is what good will starting controversy about tearing them down serve.
The burden is actually on people who want to throw out the status quo.
Personally, I don't care whether the statues are there or not. It really doesn't matter to me. I just find the gross hypocrisy and actual motives of those stirring up the controversy as repulsive as they are counter-productive to actually improving life for anyone in the nation.
Jeff Sessions can hold a huge press conference with the FOP about re-starting the militarization of local police while congratulating them on the great job they do in minority communities, and tell them how being armed like a US Army Cavalry Division will help them continue to do it even more forcefully. Yet so many "progressives" simply want to gripe about hundred year old statues and how backwards and racist they are, and wonder "why can't people have some sympathy for people whose ancestry was caught up in the slave trade?"