Earlier quoted context omitted.
It is an interesting divide. "German" is both an ethnicity and a citizenship, and it's possible to become one but not the other. "American" on the other hand is purely a citizenship, and so it is possible to become an American after immigrating.
If German is an ethnicity, I don't see why the US, which is older than the German Confederation (let alone the subsequent countries that have existed since then on that same land) has a distinct culture and set of shared values, cannot be.
Europe the Germanic people have existed way before , a country is not tied to the ethnicity.