I think Galatians 3:27,28 refers to the Jews in the body of Christ.I understand and agree with that view; but as usual I like to complicate things a bit
The whole OT was given to the Jews. Jesus ministry was for Jews only (with a few exceptions). A large part of the NT was addressed to Jews.
Does that mean none of it is for Christian use? I tend to think Jesus removed all boundaries. He died for all mankind which includes Jews.
Israel had rejected Christ and killed him, but there are some Jewish believers.True many Jews rejected Him; but many gentiles did the same.
Anyway, while I'm sure Jesus doesn't differentiate when people are in the body of Christ; I also think it's larger than that. The OT was a Jew only thing but from halfway the 1st century AD is being actively promoted to non Jews. With promotion of the Bible among the Gentiles the whole population of earth was becoming a potential "people of God".
Note: Obviously man and woman and all other mentioned groups still exist within the body of Christ. That, imo, points to the fact Israel is still set apart for a special purpose. Maybe even so while in Christ. It's just non of the groups are rejected because of what they are.
All scripture "is for Christian use," and I agree Christ "died for all mankind which includes Jews."
"All scripture is inspired by God, and is beneficial for teaching, for exposure, for correction, for discipline in righteousness, that the man of God may be equipped, fitted out for every good act." (2 Timothy 3:16)
I agree that Israel is not rejected. They are God's chosen people for the future earthly kingdom ruled by Christ which will happen when he returns. I think God has simply paused in his dealing with Israel while the nations are being evangelized.
"the nations are to be joint enjoyers of an allotment, and a joint body, and joint partakers of the promise in Christ Jesus, through the evangel" (Ephesians 3:6)
Romans 9-10 answer an abundance of these questions when read in context with each other!
Has God then cast away His people ? God forbid ! (Rom 11:1)
Romans 11:15-26 KJV
 For if the casting away of them be the reconciling of the world, what shall the receiving of them be, but life from the dead?  For if the firstfruit be holy, the lump is also holy : and if the root be holy, so are the branches.  And if some of the branches be broken off, and thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree;  Boast not
against the branches. But if thou boast, thou bearest not the root, but the root thee.  Thou wilt say then, The branches were broken off, that I might be graffed in.  Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear:  For if God spared not the natural branches, take heed lest he also spare not thee.  Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shalt be cut off.  And they also, if they abide not still in unbelief, shall be graffed in: for God is able
to graff them in again.
 For if thou wert cut out of the olive tree which is wild by nature, and wert graffed contrary to nature into a good olive tree: how much more shall these, which be the natural branches , be graffed into their own olive tree?  For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits;
that blindness in part is happened to Israel, until the fulness of the Gentiles be come in.  And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob:
Romans 11:29-30 KJV
 For the gifts and calling of God are without repentance
.  For as ye in times past have not believed God, yet have now obtained mercy through their unbelief: …
Romans 11:31-36 KJV
 Even so have these also now not believed, that through your mercy they also may obtain mercy.
 For God hath concluded them all in unbelief, that he might have mercy upon all.  O the depth of the riches both of the wisdom and knowledge of God! how unsearchable are his judgments, and his ways past finding out!  For who hath known the mind of the Lord? or who hath been his counsellor?  Or who hath first given to him, and it shall be recompensed unto him again?  For of him, and through him, and to him, are all things: to whom be glory for ever. Amen. …