St. Luke wrote the first icon of the Theotokos with our Lord.
There are many other early icons and bass reliefs of OT saints as well.
The Assyrians don't have icons because of their lack of saints.
You are looking at this rather one-sidedly. Many scholars have noted that by at least the fourth century, the Church was rather iconoclastic--an attitude primarily shaped by her opposition to pagan cultic images. Tertullian was one of the first to demonstrate such an attitude. The pagan writer Celsus, in attempting to expose a double-standard in the Christian opposition to the pagan use of idols and images, refers not to Christian iconography but the Christian anthropological conception of man as being in the "image of God." Origen's response shows no interest in defending Christian iconography over and against pagan images and idols, but rather focuses on the precise subject of Celsus' objection. Origen is generally quite dismissive of image-making in general. Both Eusebius of Casarea and St Epiphanius of Salamis, the former being pro-Origen and the latter being anti-Origen, denounced images that depicted Christ.
When you look at the broader evidence the picture you get of the historical development of iconography is not as rosy as one might want to expect. Yes, there were examples of Christian iconography in the early centuries which indicate that the practice was at least in its infancy, but such a practice had not yet become normative or universally accepted. The wider Theological, Christological and Eschatological issues that lead to its becoming standard practice within the Churches were not borne in the conscience of the Church until much later.