I see it differently. The king is God who prepaired a heavenly banquet for his son. The servants are OT prophets called to summon Israel. Because some of the invited guests ignored the prophets and others killed them, God destroyed their city Jerusalem (21:7). Then other servants were sent as apostles to invite Gentiles, bad and good to the celebration (21:10). Then out of everyone who is invited, those lacking proper attire (righteous deeds) are cast into the darkness of eternal punishment. The whole point is highlighting God’s impartial treatment of all who are called- Jews and Gentiles. He rewards and punishes on the basis of one’s acceptance or rejection of his call.
By your stubbornness and impenitent heart, you are storing up wrath for yourself for the day of wrath and revelation of the just judgment of God, who will repay everyone according to his works: eternal life to those who seek glory, honor, and immortality through perseverance in good works, but wrath and fury to those who selfishly disobey the truth and obey wickedness. Yes, affliction and distress will come upon every human being who does evil, Jew first and then Greek. But there will be glory, honor, and peace for everyone who does good, Jew first and then Greek. There is no partiality with God. (Rom 2:5-11)