The U.S. with all its equality schtick opposed recognition of slavery as crime?

Explain to me, like I’m a kindergartner, how it is possible that the “land of the free and home of the brave” was only one of three voices of opposition to international recognition of slavery as the greatest crime against humanity ever committed? Tell me why a resolution that acknowledges the very real and very true use of human beings for free labor is not endorsed by a nation whose whole schtick is that “all men are created equal?” This is disgusting. It’s revisiting a shameful era of our collective history, and Trump just… bows out? And before you say, well we weren’t the only ones, please note that the two nations who joined us were Israel and Argentina- two governments world renowned for their poor humanitarian records. Two governments who consistently put their own selfish objectives above the will of their own people. The world is watching. What’s your move?