While I am most certainly American, "American" isn't an ethnicity in the way "English" is. Americanism is about political citizenship, not ancestry.
American is an ethnic group, though we tend to prefix it with "Native." The problem is that we in the United States of America also use the word "American" to mean "a citizen of the United States of America," which tends to confuse the issue.
Fair enough, but I'm still not ethnically American.
