Nothing about Jews in these verses.
1Cor 14:21; In the Law it is written, "BY MEN OF STRANGE TONGUES AND BY THE LIPS OF STRANGERS I WILL SPEAK TO THIS PEOPLE, AND EVEN SO THEY WILL NOT LISTEN TO ME," says the Lord.
Paul is quoting the old testament scripture to the Jews.
In the Old Testament, we read this about tongues…
Isaiah 28:11 Very well then, with foreign lips
and strange tongues God will speak to this people,
12 to whom he said, “This is the resting place, let the weary rest”;
and, “This is the place of repose”—
but they would not listen.
Now read what the New Testament says about tongues, Paul is quoting that Old Testament scripture about tongues…
See Paul is quoting the old testament:
1 Corinthians 14:21 In the Law it is written:
“Through men of strange tongues
and through the lips of foreigners
I will speak to this people,
but even then they will not listen to me,” says the Lord.
22 Tongues, then, are a sign
, not for believers but for unbelievers; prophecy, however, is for believers, not for unbelievers.
1Cor 14:22; So then tongues are for a sign, not to those who believe but to unbelievers; but prophecy is for a sign, not to unbelievers but to those who believe.
It's about believers and unbelievers. Not about Jews and non-Jews.
It is about a sign to the Jews.
Please note that the word for languages is the word “tongues,” see Acts 2:11.
In Acts 2:5 we see that there were JEWS from EVERY NATION. The Jews are the people God said that He would speak to through men of strange tongues…
Acts 2:5 Now there were staying in Jerusalem God-fearing Jews from every nation under heaven.
In Acts 2:6 we see that the Jews from every nation spoke in many different languages…
Acts 2:6 When they heard this sound, a crowd came together in bewilderment, because each one heard them speaking in his own language.
Just look at the list of places the Jews had come from…
Acts 2:8-Then how is it that each of us hears them in his own native language? 9Parthians, Medes and Elamites; residents of Mesopotamia, Judea and Cappadocia, Pontus and Asia, 10Phrygia and Pamphylia, Egypt and the parts of Libya near Cyrene; visitors from Rome 11 (both Jews and converts to Judaism); Cretans and Arabs-we hear them declaring the wonders of God in our own tongues!”