the answer to this question is claim
In the excerpt from Gary Soto’s short story "Like Mexicans.” The complex narrative structure used in the excerpt is an example of establishing a work of fiction that is based on nonfiction. For the reason that the author assumes responsibility for the truth or accuracy of the events, people, or information presented thus being noted as Nonfiction.
The main idea is basically that anyone, no matter what they're believed to have done, deserves to be considered by a non-biased group of citizens.
I would agree with you - the conclusion should leave readers with an important thought at the end.
This thought should never be new, or opposing to the previous ideas you had been writing before. It also shouldn't be confusing, but quite conversely - it should explain everything and put everything in place.
