Or maybe present them as they were, perhaps through explanatory plaques to go along with the statues, portraits and monuments: "To someone who did a lot of good for America through A, B and C, but also ratified/genocided/did whatever else we now know to be bad".

It probably wouldn't hurt to have commemorative objects of Indian leaders and country-shapers as well (of which I have no doubt there a good number), to present something more "complete" regarding American history (which, like any nation's history, is complicated and more like a series of connected creeks and streams than a single river sequence of events).