In today's gospel reading, Mark 6:1-6, that question is thrown into sharp relief by the crowd's reaction to Jesus. Who is this Carpenter? Where does Jesus get all this stuff He's showing us?
Benedict XVI wrote helpfully about this issue as Joseph Cardinal Ratzinger in Einführung in das Christentum.
"Christian faith recognizes in Jesus of Nazareth the exemplary human being. This seems to be the best way to understand Saint Paul’s idea that Christ is “the last Adam” (1 Cor 15:45). But it is precisely as the exemplary human being, as the classic example of the human being, that Jesus transcends the limits of what is human; only by means of that is he the truly exemplary human being.
For the human being is truly himself to the extent to which he is with another. He finds himself only in leaving himself; he only finds himself through another… And in the final analysis, the human being is geared towards… the one who is truly other, towards God…
He is entirely himself when he ceases to remain in himself, to be turned in on himself, to affirm himself, when he is nothing but opening to God.But so that the human being might become fully human, God must become man. It is only then that… the passage from the “animal” to the “spiritual” is definitively accomplished. Then, the earthly being, looking beyond himself, can say “You” to God.
It is this opening to the Infinite which constitutes the human being… And this is the one who is the most human, the true Adam, the one who is the most unlimited, who not only enters into contact with the Infinite, but who is one with him: Jesus Christ…If the true essence of the human being as God imagined him is manifested fully in Jesus, he cannot be destined to form an absolute exception, a curiosity…
His existence has to do with the whole of humanity… He is destined to gather together in himself the whole human race. He must “draw to himself” all of humanity (Jn 12:32) so as to form what Saint Paul calls the “Body of Christ."
Gather us in, Lord. Make us like your Carpenter Son.