In the parable of the great banquet, Jesus is revealing truths about the nature of the kingdom; the make up and essence of God’s rule/reign on earth, in and through Himself.
What we find is that the kingdom challenges us to reorient everything we think to be right: our identity and relationships, how we use our resources, our definition of success, etc. In this reorientation is an invitation to participate in the kingdom, and those once thought to be rejected and cast out, are actually the most important guests.