How did the works of jan van eyck and rembrandt reflect a human-centered naturalism?

Human-centred naturalism is the idea that individuals and everyday life are effective and convivial vehicles for artistic expression; in particular, both Flemish painters portrayed figures in visceral poses, conveying raw human emotion through the use of a rich, deep palette with highly contrasting colors. They were both noted in Renaissance art and painted in unique manners, which are noted throughout art history as being "masterful" works of art.