Why don't American immigrants from Europe and Africa call themselves Europe and Africa?

At the beginning of the birth of the United States, mainly European immigrants gathered immigrants from Britain, France, Italy, Germany and other European countries, and took black slaves across the ocean to the country created by North America.

The open and inclusive social and political environment makes the United States a melting pot of the nations of the world. Whether white or black, Asian or European, they are all Americans.

Regardless of their origin and color, they will proudly call themselves the American people; So they don't deliberately emphasize their race and origin.