There shall be weeping and gnashing of teeth, when ye shall see Abraham, and Isaac, and Jacob, and all the prophets, in the kingdom of God, and you [yourselves] thrust out.
Note 5 at Lu 13:28: This passage is speaking of judgment and applies to all who reject God's salvation through Jesus. However, in context, the specific application was to these Jews and the Jewish nation. Jesus was saying that Abraham, Isaac, Jacob, and the prophets would be in the kingdom of God, but these Jews wouldn't. They thought they would be saved because they were Jews. They were trusting in their genealogy and not in a Savior. They thought they would obtain salvation by natural birth and were ignorant of the new birth (see note 2 at Joh 3:3).
Lu 13:29 goes on to speak of people coming from the east, the west, the north, and the south and entering into the kingdom of God. This is a reference to the Gentiles being granted admission into the kingdom of God (see note 2 at Lu 2:32 and note 45 at Mt 6:32), and it infuriated these Jews. As explained in note 4 at Lu 13:26, they believed they would be saved by association with God as His chosen people, and they couldn't accept that anyone who wasn't a Jew could make it.
The statement in Lu 13:30 about the last being first is also in reference to the Gentiles and Jews. The Jewish nation was first in the sense that they were given the covenants and the greater opportunity to know God. But they would become the last in the sense that they rejected Jesus as their Messiah; salvation would be taken from them and given to the Gentiles (Ro 11:11).