Abraham Lincoln was not a white supremacist, he was a white nationalist, which is almost as irrational.
I don't know who Margaret Sanger is nor do I care to research her,
and yes, Robert E Lee was a much more moral person than Abraham Lincoln. Abe Lincoln was an imperialist who should have let the Confederate States of America alone. Imperialism is inherently evil, I lived back when the Southern States succeeded I would have joined the Confederacy because they were pro-states-rights, pro-community, and pro-democracy.
Even the symbols under Abe's arms on his memorial are FASCIST symbols. The fascis are what they are called, and they were used by the Italian Fascists. Ugh.