[SuperLuke]

In my own opinion, I would ask myself, “What kind of narration demo do I want?” before I pick something to narrate in my demo. Since you picked this one about psoriasis, I’m guessing you want to make a demo that reflects you as a nonfiction narrator for an article that you may find in a medical journal or a documentary.
As far as your performance and recording quality, good job narrating without having to take a breath in between sentences. You were audible and clear. If you are trying to sound like a documentary, you’re on the right path.