The term “Americans” has been used to describe people from what is now the United States since LONG before the United States existed. The term can be found as far back as the late 17th century to describe residents of the Colonies, and yes, I’ll get a cite if anyone wants it.
This debate wouldn’t have happened if they’d just called the damned country “America.” Screw this long name stuff. I like Canada - the official name is “Canada.” (No, it is not officially called “Dominion of Canada.”)
The worst is “The United Kingdom of Great Britain and Northern Ireland.”