“It was the American Revolution that caused people to question slavery. No one had questioned it before we decided as Americans that we are endowed by our creator with unalienable rights.”
That is just too funny. The US was one of the last countries to abolish slavery. And your slave-owning revolutionary leaders (founders and framers) wrote features of slavery into the constitution.
In England, we have never had a law making slavery legal. But in 1772 (ie before the declaration of independence in 1776) it was made illegal. The American revolutionaries were fighting against the country that was in the vanguard of the abolition movement.
The US waited until 1865 to abolish slavery. Very, very late. Embarrassing, obviously. You were the baddies. We were the goodies!!!
ps oh yes, and the Declaration didn't limit the unalienable rights to Americans. It claimed them for all "men" (ie American and non-American males). Small but significant point.
This all sounds a lot like the American claim to be the first democracy. It works only if you work very hard on narrowing the definition to suit the claim. eg being a slave-owning country doesn't count; the votes of women don't count.
The US hasn't led on everything. It's not that it's bad. It's just more similar and less special than it wishes to be. But it does have a unique need to be seen to have been the first to do anything that later seems like a good idea.