What makes N.C. Wyeth important is that he blended the concepts of impressionism and portraiture with illustration. He specifically chose to use dramatic light sources, stark, arresting color uses, and the emphasis of action and movement over detail and portraiture.
Wyeth used those ideas to give a movement to his characters that have become the standards for how these stories are told.
Pay attention to his uses of light sources in particular. Everything is exaggerated, with the emphasis on drama and story.
"Comics should be the maximum amount of information in the least amount of panels." - Will Eisner.
N.C. Wyeth and his peers’ illustrations are the DNA of heroic action figure drawing, and comic books in particular have been drinking from that well since the very beginning.
People do things more dramatically in comics because it is like the actors on a stage, shouting their lines and intentions for even the cheapest of seats to hear, with highly exaggerated emotional reactions to the jokes and so on. It happens on every TV show, every movie, and comic out there. Communicating visually, is the point.
N.C. Wyeth turned stories from History books into stories of chivalry, adventure, cowboys, Native Americans, Gun Fighters, and of course, Pirates.