In the parable there are two groups. The originally invited group representing the jews, and the larger indiscriminate group representing gentiles. As far as amounts go, the first, the Jews, is few, the second, the gentiles, is many.Matthew 22:14: "For many are called, but few chosen."
Mat 22:11 And the king coming in to look over the guests, he saw a man there who did not have on a wedding garment.
Mat 22:12 And he said to him, Friend, how did you come in here without having a wedding garment? And he was speechless.
Mat 22:13 Then the king said to the servants, Bind him hand and foot and take him away, and cast him into outer darkness. There shall be weeping and gnashing of teeth.
Mat 22:14 For many are called (κλητοι), but few chosen (εκλεκτοι).
First of all, it is God that does both the calling and the choosing (election). Calling is not some external announcement of the Gospel, it is internal working of God. That’s made clear because verse 13 uses figurative language about hades/hell so the entire parable has eschatological ramifications (outer darkness, weeping, gnashing of teeth).
Second of all, what role does man play? Let’s look at Prov 1:24:
Prov 1:24 Because I have called, and ye refused; I have stretched out my hand, and no man regarded;
It is man who does the refusing or the reverse of refusing, i.e.: accepting. Synergy is manifested in all its facets.
Third of all, the fact that the number of people ("many") called by God decreases to the number of people ("few') elected by God hits hard at both the Irresistible Grace and the Preservation of Saints theories.
The Jews, the few, were chosen on earth to be His people on earth, the many are callled to be His in eternity.