Schaff, Philip. History of the Christian Church (The Complete Eight Volumes in One). Amazon Kindle Edition, 2014.
Volume 2, Ante-Nicene Christianity A.D. 100-325, “Chapter 6. Christian Art” (Includes sections 75-81).
§ 80. Allegorical Representations of Christ.
Jesus himself is not depicted very early, probably because the apostles never told us what he looked like (Schaff 2014, Loc. 15755). As someone who was seen both in a state of humiliation and exaltation, Jesus may have appeared very differently at various times (Schaff 2014, Loc. 15760). Once he is depicted, he most often appears with sheep or fish, referring to events in the Gospels.
§ 81. Pictures of the Virgin Mary.
Schaff asserts that there are pictures of Mary which may date back to the second or third century (Schaff 2014, Loc. 15804). She normally appears with the baby Jesus and others related to the Nativity. It is not until the fifth century that Mary appears as the queen of heaven, the one praying for us (Schaff 2014, Loc. 15820).