That’s because the United States had existed as a nation for less than 250 years. We’ve had a pretty crappy record since then.
Allowed slavery and Jim Crow laws for the majority of our history, kicked native Americans out of wherever they lived to get more money. Literally fought a war over whether slavery should be allowed.
Don’t forget the imperialist expansion era. Completely screwed over the Philippines and Cuba in particular.
The vast majority of their military involvement in central and South America was to protect financial interest at the expense of local citizens. During the Cold War era this continued but instead served to unseat communist politicians and often put corrupt dictators in their place (look up operation PBsuccess).
the US also didn’t allow in many Jews during the pre WW2 and WW2 era prosecution in Europe. Anti-Semitism was pretty well tolerated until Pearl Harbor.
There’s the Vietnam war of course, all the pointless intervention and death in the Middle East.
Mass incarceration and the war on drugs.
I could go on and on. The US is not a clean country. Go back to history class.