The word "American" has many sub entries in the Oxford English Dictionary - not all of those meanings are "citizen of the USofA".

So much for unambiguous.

Have you ever actually heard it used in conversation or writing where the speaker's intention was a meaning that included people outside of the USA? I haven't.

I have, yes.

I note, also, that you didn't ask if anyone

> " heard it used in conversation or writing where the speaker's intention was a meaning that included people outside of America? "

which further explans why non-USAians like myself adopted the practice decades past of prefering clarity for precision.