In the Prologue to Oedipus the King, the priest mentions boys, young men, and multitudes. Whom does he represent?

The priest would represent the church. The Priest's followers make sacrifices to the gods at the beginning of the play, hoping that the gods will lift the plague that has struck the city. At this point, the followers believe that the Gods have punished the city for some sin that must be rooted out. Oedipus, then, takes it upon himself to visit the Oracle to determine whose sin it is and for how it might be atoned.