How would someone relatively close to the invention of coffee, like say a 14th century North African, take their coffee? How would taste in comparison to a modern day homebrew? Have the beans changed overtime?
Original coffee is not going to taste like modern American coffee, because it isn't made the same. The oldest form of coffee is often called Turkish coffee, where the water is boiled, sugar added, finely ground coffee added, and the whole slowly brought back to the boil. It's served with the grounds in the cup. In some places like Morocco, spices are added to the grounds. Some traditions don't use sugar.
Of course, flavour varies by the bean and where it is grown. Robusta beans are harsher than arabicas, for starters. I used to keep a half dozen different coffees in the house, including a brand a friend sent from a grocery in Spanish Harlem. Brands work hard to keep their blend tasting the same year after year, while Gevalia sells year-marked pure types.
Sources: Hale, The Horizon History of Eating and Drinking
Several Middle Eastern cookbooks. I like best Time-Life's old The Cooking of the Middle East.
Too much time hanging around a coffee store.