Justin Martyr, an early Christian apologist of the second century C.E., was adamant that Jesus was an apostle:
And he [i.e., Jesus—JNT] is called both messenger and apostle [ἀπόστολος], for he declares whatever we ought to know, and he is sent forth to declare what is revealed; as our Lord himself says, “The one who listens to me, listens to the one who sent me.” (1 Apology 63:5)
Today we usually think of Jesus as the one who appointed apostles, and to hear of Jesus himself being referred to as an apostle can sound jarring. But while referring to Jesus as an apostle might seem strange to Christians in the twenty-first century, this designation for Jesus would not have sounded strange to early believers.
Understanding the ancient Jewish institution of the shāliaḥ, or apostle, gives us a unique glimpse into Jesus’ self-perception. Jesus regarded himself as the apostle of God, which is to say, God’s official representative on earth, a divinely authorized agent commissioned to carry out God’s redemptive mission for Israel, humankind, and all creation. Such a job description is practically identical to the ancient Jewish concept of the Messiah.
-  Translation adapted from The Ante-Nicene Fathers (10 vols.; ed. Alexander Roberts, James Donaldson, Allan Menzies; repr. Grand Rapids: Eerdmans, 1980-1986), 1:184. ↩