It is sad that you do not recognize nor understand what you are reading there in Romans 9.
In truth, verse 8 pretty much denies so much of what you believe and post here. You profess over and over that the covenants and salvation are to the children of the flesh. Verse 8 says that is not true and instead it is the children of the promise.
Paul caps that portion of the discussion with verses 30-33 with the following:
Rom 9:30 What shall we say then? That the Gentiles, who followed not after righteousness, attained to righteousness, even the righteousness which is of faith: 31 but Israel, following after a law of righteousness, did not arrive at that law. 32 Wherefore? Because they sought it not by faith, but as it were by works. They stumbled at the stone of stumbling; 33 even as it is written, Behold, I lay in Zion a stone of stumbling and a rock of offence: And he that believeth on him shall not be put to shame.
He, Paul, adds to that discussion in chapters 10 and 11 which you really need to spend some time studying carefully because again he essentially rebuts most of what you post here concerning the condition and the position of the race of Jews.
What exactly is that "stone of stumbling"? What is a "rock of offense", and why a rock? A rock is hard, it is weighty.
The answer is found in the event that occurred in the book of Numbers.
In the Old Testament the "serpent" or "snake" represented two things that on the face contradict each other.
6 And the LORD sent fiery serpents among the people, and they bit the people; and much people of Israel died.
7 Therefore the people came to Moses, and said, We have sinned, for we have spoken against the LORD, and against thee; pray unto the LORD, that he take away the serpents from us. And Moses prayed for the people.
8 And the LORD said unto Moses, Make thee a fiery serpent, and set it upon a pole: and it shall come to pass, that every one that is bitten, when he looketh upon it, shall live.
9 And Moses made a serpent of brass, and put it upon a pole, and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived.
Numbers 21:6–9.
The serpent/snake was the very animal that
deceived the woman and represents that as well as "cunning", "evil", and "sin." In their minds it has a negative connotation, even that of being "adversary."
In the Book of Numbers, the image of the serpent takes on a unique and seemingly opposite meaning: healing and deliverance and prefigures Christ. But it was after the resurrection that is represents Christ. The serpent in the OT represents the poison of sin and the power of the Adversary (Genesis 3), but the brass serpent on the pole represents the divine provision for healing and salvation from that very poison.
At Pentecost and beyond that when Jews were becoming "born-again" by the thousands daily (Acts 2:47), and the story of the death of Jesus the Christ/Messiah, Lord, and King made its rounds these Jewish Christians returned to their homes and synagogues with an outline of Peter's sermon, testimony of Jesus the Christ, and their experience with the Holy Spirit of Promise, the New Covenant prophesied by one of their prophets, Jeremiah, was on everyone's minds. It was exciting, and this "new thing" God was doing 'in the earth' took center stage in conversations among the people. But soon, God's Divine provision for healing and salvation came with a pre-installed difficulty that the Jews could not all wrap their minds around. How can a thing cursed of God - the serpent of Genesis - also be intertwined with a message of hope and deliverance and salvation? The Law states that anyone that hung on a tree was cursed. How can a person (Jesus) who hung on a tree (cross of wood) and cursed of God also be their King? It was offensive. It was very difficult to reconcile in their Jewish minds. In the beginning these "Christians", these followers of Jesus the supposed Way (to the God of Abraham) was being witnessed among the Jews and the more traditional Jews "balked" at the thought that their Messiah, Lord, and King was also an object of cursing and judgment form God. As what happened to Saul, the beginning saw first Jews that blasphemed the thought which led to persecution and then injury (killing).
12 And I thank Christ Jesus our Lord, who hath enabled me, for that he counted me faithful, putting me into the ministry;
13 Who was before a
blasphemer, and a
persecutor, and
injurious: but I obtained mercy, because I did it ignorantly in unbelief. 1 Timothy 1:12–13.
In Acts 7 Luke records these hardened Jews attack and kill a man named Stephen and Saul was one of the perpetrators. In Acts 8 outright persecution and injury was leveled against this new sect of "Judaism" and Christian Jews were being attacked by their brethren the Jews.
1 And Saul was consenting unto his death.
And at that time there was a
great persecution against the church which was at Jerusalem; and they were all scattered abroad throughout the regions of Judaea and Samaria, except the apostles. Acts 8:1.
The apostles did not obey Jesus to go to Samaria, Judaea, and the uttermost parts of the earth where Jews lived among Gentiles to herald the good news of Messiah's advent, it was the common folk. The gospel message did go out but it was by the born-again Jews God through persecution caused to scatter and, in their scattering, told other Jews what happened to them (Pentecost) and what transpired to a Jew who claimed to be king and deliverer of the people of Israel.
That "stone of stumbling" and "rock of offense" Jews could not get past was the testimony of the people who witnessed it how a man who 'hung on a tree' and was cursed of God was also their Savior and King. For the most part Jews were a sensible people, but this fact as testified by others about Jesus also caused great alarm and dismay because in their minds Jesus' crucifixion was a stumbling stone they could not get past to see also the other side of that "fiery serpent on a pole" and the "curse among the people" was indeed their long-awaited Son of God and Savior of the Jewish people.
30 What shall we say then? That the Gentiles, which followed not after righteousness, have attained to righteousness, even the righteousness which is of faith.
31 But Israel, which followed after the law of righteousness, hath not attained to the law of righteousness.
32 Wherefore? Because they sought it not by faith, but as it were by the works of the law.
For they stumbled at that stumblingstone;
33 As it is written, Behold, I lay in Sion a stumblingstone and rock of offence: and whosoever believeth on him shall not be ashamed. Romans 9:30–33.
Along with the ability of the Spirit of Promise to open men's hearts (Lydia) He came with the power to harden their hearts and force violent conflict. And these mixed-race "Gentiles" that never "followed after righteousness" because they grew up in Gentile lands heavily influenced by Greek culture and were "[at]
that at that time were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world" (Eph 2:12) knew nothing of their Hebrew heritage, their culture and their religion (Law of Moses) because they did not trust the prophets - Moses, Jeremiah, and Isaiah - who prophesied exactly the miraculous birth of their Savior and the lamb led to the slaughter by the God of Israel. God Himself gave the Hebrew people a fiery serpent on a pole/cross and told the people to "look on 'it'" in order to be saved. They stumbled at that stumbling stone", that "rock of offense" that offended their sensibilities and brought with it judgment as well as healing and salvation. To them the 'letter of the Law' was so ingrained in their consciences they could not - without the Spirit's help - understand the 'spirit of the Law' in order to be saved. It was a vicious 'catch-22', God had put into their deliverance and redemption that many could not see through because God had blinded their eyes and "therefore they could not believe, because that Esaias said again, He hath blinded their eyes, and hardened their heart; that they should not see with their eyes, nor understand with their heart, and be converted, and I should heal them" John 12:37–40.
Without this 'stopgap' placed intentionally into the gospel message of salvation by God millions more Jews would be saved and not just thousands day by day. The evangelistic fervor prophesied for Israel in the last days would have been short-circuited' and Jesus would have returned within days, exactly what their Jewish minds also understood by Jesus' last words, "I will come again."