Canadian here. “American” means from the US. People from the rest of the continent don’t care. They’re the ones with the dumb country name that doesn’t have a more obvious demonym. But we’ve all collectively agreed that that’s what it’s called.
If you want to refer to someone from South America you say South American. If you want to refer to someone from North America you say North American.
Most americans (IE the americas, which include central and south america, and the carribbean), really dislike the usonians usurpation of the term “america” to refer solely to the United States, which really only started in the early 1900s as the US got really forward about its imperialist interests. You’re only hearing “americans mean only US citizens” from the nation that excludes most americans.
Counterpoint: there is no continent named “America.” “North American,” “South American,” and even “Central American,” or “Latin American,” for added specificity, are completely sufficient demonyms for the denizens of the continents (and subreigon) writ large.
