This website contains age-restricted materials including nudity and explicit depictions of sexual activity.
By entering, you affirm that you are at least 18 years of age or the age of majority in the jurisdiction you are accessing the website from and you consent to viewing sexually explicit content.
American is pretty unambiguous. What are you getting it mixed up with? No one else uses it. If you hear American, do you have to run through a list of other countries asking them which they are from? Of not, it’s unambiguous.
You could argue that it shouldn’t be the pronoun for a US citizen, but that’s a different argument than it being ambiguous.
Whatever adjective makes you feel better: appropriate, apt, fitting, correct, modest, less expansive, less assuming, less imperious, less opulent, less grandiose, less egocentric, less narcissistic