Ingersoll's metaphor "every beautiful thought is a teacher" affects the meaning of the interview in the following way:
It conveys the idea that people can learn from the thoughts they have.
Ingersoll is talking about the effect a play can have on an audience, and since a play is a form of art and it can make people think and reflect upon countless topics and issues, it can also lead people to have beautiful thoughts and consequently learn from them, since those thoughts are teachers in Ingersoll's point of view.
I think that the best choice for this would have to be Paragraph 6, I could be wrong but I'm pretty sure I'm not. The reason I think that paragraph is the correct option is because it provides more detail, but what really sold me is the line that says "....and enable African Americans to better integrate into American society as a whole.” That shows that they are given opportunity to show off their works and make a better living for themselves, which is exactly what this question is asking/looking for.
“Artists held the belief that through intellect, literature, art, and music, their work could challenge racism and enable African Americans to better integrate into American society as a whole.” (Paragraph 6)
First of all/ Which Shiloh book are you talking about?
You could use the library or the internet when you're considering a topic to write about so you know all you need to when you are writing it.
hope this helps!