These chapters are about salvation though. You have to understand the prevailing thought during this time by the Jews was that only those who were genetically descendants can come to salvation. We see this when Peter is called to go to Cornelius house.
27 And as he talked with him, he went in and found many persons gathered. 28 And he said to them, "You yourselves know how unlawful it is for a Jew to associate with or to visit anyone of another nation, but God has shown me that I should not call any person common or unclean. 29 So when I was sent for, I came without objection. I ask then why you sent for me." (Acts 10:2729, ESV,
https://ref.ly/Ac10.27-29;esv)So Paul is teaching who are the descendants of Abraham and the inheritors of the promises.
But it is not as though the word of God has failed. For not all who are descended from Israel belong to Israel, 7 and not all are children of Abraham because they are his offspring, but "Through Isaac shall your offspring be named." 8 This means that it is not the children of the flesh who are the children of God, but the children of the promise are counted as offspring. 9 For this is what the promise said: (Romans 9:69, ESV,
https://ref.ly/Ro9.6-9;esv)Paul is making the case here it is not about genetics.
30 What shall we say, then? That Gentiles who did not pursue righteousness have attained it, that is, a righteousness that is by faith; 31 but that Israel who pursued a law that would lead to righteousness did not succeed in reaching that law. 32 Why? Because they did not pursue it by faith, but as if it were based on works. They have stumbled over the stumbling stone, 33 as it is written,
"Behold, I am laying in Zion a stone of stumbling, and a rock of offense;
and whoever believes in him will not be put to shame." (Romans 9:3033, ESV,
https://ref.ly/Ro9.30-33;esv)Here Paul is describing how one becomes a descendant. It's by faith.
"Everyone who believes in him will not be put to shame." 12 For there is no distinction between Jew and Greek; for the same Lord is Lord of all, bestowing his riches on all who call on him. 13 For "everyone who calls on the name of the Lord will be saved." (Romans 10:1113, ESV,
https://ref.ly/Ro10.11-13;esv)Paul then makes the point for all who believe there is no distinction. (Which your view point is saying there is)
Then we get to 11. Paul's making the point the Jews have not been rejected because they were under the law but are now free to be under grace. Jews have no barrier to becoming Christians based on having previously being under the law. Which is a big point for those at that time under the law.
As we can see in chapter 11 it mentions there is ONE HOLY tree that make up the descendants of Abraham. Which is based on faith for both Jews and gentiles has equal opportunity to be in.
What it is not teaching is that there are two separate people groups of God and that there are two separate sets of promises. Which is what your view is.
14 For all who are led by the Spirit of God are sons of God. 15 For you did not receive the spirit of slavery to fall back into fear, but you have received the Spirit of adoption as sons, by whom we cry, "Abba! Father!" 16 The Spirit himself bears witness with our spirit that we are children of God, 17 and if children, then heirsheirs of God and fellow heirs with Christ, provided we suffer with him in order that we may also be glorified with him. (Romans 8:1417, ESV,
https://ref.ly/Ro8.14-17;esv)ALL who are led by God are sons of God. Again we see unity here not separate people groups under God. And it says we are Joint heirs with Christ. What are we jointly inheriting? Do you think Jews are inheriting something different? If so you have to conclude it's not from Christ because Christians are joint hers in full.