For your information:
- According to Slavery In America, 500,000 slaves were brought to America. Many more were taken to the Caribbean and South and Central America.
- According to the Anti-Slavery Society, there are 2.7 million slaves in the world today, while others estimate up to 27 million (using a different definition).
It does not excuse what happened here in the least. Those other places never even pretended to have any respect for human rights.
We did commit to that concept of "endowed by our Creator with inalienable rights to life, liberty and the pursuit of happiness."
Yet we failed miserably when it came to slavery. Be honest about it. We failed in that regard. You can't brush that aside by saying others were even worse.