Param, you misread the assignment. You were only supposed to write one paragraph, the introduction to an imaginary essay over why “Introduction to Picturing Frederick Douglass” would or would not be a credible secondary source. You were not to actually write such an essay. All I needed to see is whether or not you are able to accurately evaluate a secondary source for credibility, and you could tell me that with a thesis and three supporting points. Unfortunately, you didn’t do that here, not even in the entire essay. Why? Because your proof that Gates’ essay is credible is found in the content he gives. You have bought into the content he’s selling before vetting whether that content is credible. Do you see the difference?
Rewrite your introductory paragraph, basing your evaluation on the CRAAP Test, and resubmit.