Irenaeus concluded—amazingly—that Adam came into being as a result of Christ and his passion, that Adam was made in the image of the incarnate Christ, who himself is the beginning and the end.
From Beginnings: Ancient Christian Readings of the Biblical Creation Narratives by Peter C. Bouteneff. Here it is with more context (including several other profound points):
Adam as the sinner is the antitype of Christ as the glorious; indeed, the Jewish tradition that saw Adam as a priest, a patriarch, and a king, was utterly transformed in early Christian thinking, which saw Adam as failing in all these vocations and Christ as fulfilling them. The glory of Adam became the glory of Christ. The modern word “typology”—expressing this relationship and so many of the characters and features of the OT with those of the NT—hardly does justice to the transformative thrust of Christian thinking.
…One of the fullest expressions of this thinking came from Irenaeus, who interpreted the Lukan genealogy together with Romans 5:14 to mean that Christ joins the end to the beginning, recapitulating in himself all nations, languages, and generations. Irenaeus concluded—amazingly—that Adam came into being as a result of Christ and his passion, that Adam was made in the image of the incarnate Christ, who himself is the beginning and the end. This trajectory of thinking, which cannily stands temporal chronology on its head, was definitive for the patristic era and right on through the fourteenth century in Nicholas Cabasilas, who puts it this way:
It was for the New Man that human nature was created at the beginning. . . . It was not the old Adam who was the model for the new, but the new Adam for the old. . . . For those who have known him first, the old Adam is the archetype because of our fallen nature. But for him who sees all things before they exist, the first Adam is the imitation of the second. (The Life in Christ 6.91–94)
“Typology” must be understood against the backdrop of this reconfiguration of history, which, then, began not in some calendrically datable time five thousand, six thousand, or even 13.7 billion years ago, but with Christ and his incarnation and, even more, with his passion. Indeed, to the extent we dwell with the fathers in this perspective, the significance of the age of the world is entirely limited to the sphere of science and bears no theological significance whatsoever.