But in the books of the NT actually attributable to Paul he basically is dead silent about an earthly Jesus
Yes, because he didn't know the earthly Jesus and had to compete with those who did. Yet he still gives us nuggets of Jesus' teachings (most directly the one on divorce), tells us about Jesus' final meal, states that he was descended from David according to the flesh (very earthly) and that he was crucified. He also tells us he knew Jesus' brother.