Just looked at this parable with a group and started with the question where is God in the parable?
If see God as with the poor and marginalised he is in the highways and byways. Using this as the startpoint you don’t have the option of seeing the king as god or the son as Jesus and could see the parable as a critique of organized religion or power.
The king is keen to make alliances with the rich farmers and businessmen so invites them to the party to impress them, they are obviously powerful as they have the opportunity and means to kill the servants the king first sent, and the king needs to subdue these people after they killed the servants by the use of force with armies not just a couple of people.
Then in order to not be seen as a loser the king needs to have some people come to the party so invites (coerces?) poorer people to attend. Tradition at the time suggests the grooms father provides the right clothes for the party guests but one person refuses to wear the clothes from the manipulative, politically savvy, violent and coercive monarch. one person refuses to play the game by the rules of the powerful and is cast out into the darkness with the outcasts.
Here we see Jesus as someone not willing to go along with the power plays of the day, someone who stands up for justice, who reads the motives of the powerful and stands outside of those systems. The kingdom is heaven is about putting other people first, standing up for righteousness, speaking out for the voiceless and living in a way that is radically different to established ways of the world.
1 Jesus spoke to them again in parables, saying: 2 “The kingdom of heaven is like a king who prepared a wedding banquet for his son. 3 He sent his servants to those who had been invited to the banquet to tell them to come, but they refused to come.
4 “Then he sent some more servants and said, ‘Tell those who have been invited that I have prepared my dinner: My oxen and fattened cattle have been butchered, and everything is ready. Come to the wedding banquet.’
5 “But they paid no attention and went off—one to his field, another to his business. 6 The rest seized his servants, mistreated them and killed them. 7 The king was enraged. He sent his army and destroyed those murderers and burned their city.
8 “Then he said to his servants, ‘The wedding banquet is ready, but those I invited did not deserve to come. 9 So go to the street corners and invite to the banquet anyone you find.’ 10 So the servants went out into the streets and gathered all the people they could find, the bad as well as the good, and the wedding hall was filled with guests.
11 “But when the king came in to see the guests, he noticed a man there who was not wearing wedding clothes. 12 He asked, ‘How did you get in here without wedding clothes, friend?’ The man was speechless. 13 “Then the king told the attendants, ‘Tie him hand and foot, and throw him outside, into the darkness, where there will be weeping and gnashing of teeth.’
14 “For many are invited, but few are chosen.”