Fortunately your standards on what is a "good answer" do not apply to the real world.
They're not "my" standards. But I do agree with them, and see no good reason not to adopt them. Slavery disqualifies one as a subject for reverent works of public art. I have yet to hear anything like a convincing argument against the idea.
We put up statues to honor those individuals who made great contributions to their society, be it local or national. Those individuals may very well have flaws, but those flaws do not negate their accomplishments.
Correct. Being slave owners does not negate their accomplishments. But that goes both ways - having accomplishments does not negate the fact that they were slave owners.
So, I have a proposal:
Because they were slave owners, and therefor unworthy of reverence, let's remove these reverent idols of American civil religion. Take down their statues. And at the same time, if you want to honor them, you can still do so by learning about their accomplishments in history books.
It's win-win. No more reverent works of public art for slave owners, but we can still honor their important deeds by actually learning about them.
There may come a time when the community decides that the flaws of a certain individual outweigh the accomplishments, and the statue should be removed.
You are living in that time, right now.
In fact, it's nothing new. To pick one example of many, Penn State removed their Joe Paterno statue in 2012. This kind of reckoning happens all the time, just never on quite a scale as we're seeing today.