Have African-American influences affected only those who have endured racial injustice or has African culture grown even in the Caucasian community?
African American influences have reached every element of American society, not just those who have suffered racial injustice. Perhaps the greatest influence has been in music, primarily Jazz, a music form which is uniquely American. It consists of a blend of European and African musical traditions; and for many years was unique to the Black community. It is now a universal music form with offshoots such as blues, rock and roll, etc.
Also, the experience of slavery led to sacred music works commonly known as "spirituals" which have also affected all of American society. Examples are "Swing Low, Sweet Chariot," and "Go Down Moses." Both spirituals and jazz, both of which originated from African roots, are now an element of the American fabric. They constitute a unique contribution of African American culture to American culture as a whole.
Outside of that, an open-minded person (most likely) could not deny the impact of slave narratives, the music, the poetry, biographies, autobiographies, and the arts (very limited list of works) which are the work of both past slaves and those who feel racial injustice today.
No longer do African-Americans have to hide their talents. Instead, they can openly write, publish, sing, speak out, and paint.
Given that America is a multicultural nation, I would openly suggest that the African-American culture has grown into the American culture.