Note that Celsus's Jew is the principal exponent, in Antiquity, of the Rebel Jesus Theory, and it was based on two accusations:
- the accusation that Jesus was son of a Roman soldier;
- the accusation that Jesus was a brigand.
Not even Skanderberg was really a Turkish.
The real point of the Rebel Jesus Theory, as found in Celsus, is the anti-historical contradiction that a not-Jew was the leader of Jewish rebels.
My point is that this contradiction is found in the invention of the Barabbas episode: it was designed to address only a Roman audience. The Romans had to understand that the Jesus Son of (Unknown) Father preached by Marcion (and by proto-John, too) was really a mere Bar-Abbas, a Jewish brigand of which the father was unknown (hence, not really a Jew, therefore even a Roman soldier!).
The true Jesus was the Jesus called Christ/king "of (genitive possessive) the Jews" and Messiah of YHWH, not the Jesus of Marcion, not Barabbas.