What does all this mean?
Well it seems Peter mistakenly concluded that the apostles would earn a special reward by their response to Jesus call. Yet, Jesus assured him that there would be rewards for all people who faithfully followed Him (vv.28-29), but these rewards would be on God's graciousness not on human merit.
The regeneration is the new world order that will be ushered in with the Second Coming of Jesus and the judgment.
The twelve thrones, twelve tribes represent the 12 apostles that are the founders of God's NT people, like the 12 patriarchs of Israel.
The twelve thrones is Jesus spiritual kingdom, the church.
Israel now represents Christ' spiritual people which includes all who are truly redeemed through the death of Jesus. The language is figurative but clearly means all who follow Jesus servant role are destined for honor from God.
Judging.... well one can find this in Rev.2:26 which says,
"And all who overcomes, and keeps My works until the end to him I will give power over the nations." - Meaning at the return of Christ, Christ will share with His loyal people the sovereign authority that He has received from God.
Also in 1Cor.6:2 it states, "Do you not know that the saints will judge the world ? And if the world will be judged by you, are you unworthy to judge the smallest matters."
So we see that God's people are given Christ' sovereignty and will judge the nations of this world when Christ returns and brings in His Kingdom !!
First last, last first.... This proverb is explained by the parable in 20:1-16. God's rewards are not earned by the time we serve or the energy we expend. They are His gracious gifts to all who follow Him faithfully. God gives generous rewards for obedience and faithfulness in His kingdom, that is all who hear the gospel and obey it, amen !!
God's value is opposite of human values. True greatness is found in service, not in domination~ in the cross, not the crown !!
Blessings