You have read Romans 9 to 11? Israel rejected their gospel and has been set aside by God
There’s only one gospel. And no where in the passage you cite does say anything about “setting aside” Israel.
All Israel shall be saved; those who will finally come to believe the gospel.
The unbelieving Jews rejected it; and God knew they would. There’s no ‘Plan B’.
Romans 11:1-2,5
[1] I say then, Hath God cast away his people? God forbid. For I also am an Israelite, of the seed of Abraham, of the tribe of Benjamin. [2] God hath not cast away his people which he foreknew...[5] Even so then at this present time also there is a remnant according to the election of grace.
There’s a remnant, not a nation.
God has not cast away his people (like Paul - a believer).
Romans 11:20,23
[20] Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear: [23] And they also, if they abide not still in unbelief, shall be graffed in: for God is able to graff them in again.
Romans 9:6
[6]...For they are not all Israel, which are of Israel