The Prodigal Son is us
The father....is THE FATHER awaiting our return
The brother is probably a future reference to the Jew who would have to make room for us
Two recurring themes are also seen in this parable...
One Jesus....is down playing his own role here, and may be presumed, isn't involved in the repetence process, but He is the opportunity the prodigal grasped onto in the pig pen.
Second. In the Parable of the wedding feast and the the one where the workers who were hired for an hour were paid the same as those who worked all day, he is addressing the resentment we, or others might feel at the reward of others....and that our hearts should be A. satisified with our own rewards, and B. Be joyful at other's rewards