This is a good question. The best way to answer it is probably not through historical methods, but art historical ones. Historians deal largely with written sources. There are descriptions of physical apperance in literature and scattered in other forms of documents, but comparing a written description to modern visual appearance is iffy.

On the other hand we have a rich trove of visual art from the middle ages through today. Although much of medieval art is not as naturalistic as we might like to answer the question. If you move into the early modern period (14th-18th c.) then we get lots of depictions from the renaissance. In my mind some of the most striking examples of 'everyday' people can be found in the work of the Dutch masters. The village scenes of Bruegel. Rembrandt has many portraits and close-up scenes. You also have Van Eyck and his religious art that often featured the patrons within the scene. He also did portraits, another.

As you can see, the people in these works 'look' like people you might see today. Sure they have different clothes, but their faces capture the variety you might expect across age ranges today.

Hope that helps!