I appreciate those Scriptures but none of them identify Gentiles as the recipients of the gospels and epistles. You're looking at this from a Gentile mindset which has been molded through years of Gentile Christians attempting to usurp the covenants and promises God gave to His Beloved apple of His eye Israel.
Let's go down biblical history road:
In Acts 2 in Jerusalem the Jews are celebrating the Feast of Trumpets. The middle wall partition has separated Jews from Gentiles for hundreds of years. There are no Gentiles at this celebration. At this feast there 17 languages and dialects represented that the apostles spoke in which were the languages of the peoples that traveled from outside Jerusalem and even from Gentile lands where these Jews were living. The twelve tribes of Israel were scattered throughout the then known world.
Peter's sermon in response to being accused of being drunk so early in the morning was addressed to the Jews at this celebration for the twelve tribes were there and heard Peter speak.
Even before Peter ended his sermon the Holy Spirit moved upon the people and Scripture says God added 3000 Jews to His Church, which was a continuation of the Church in the desert at the time of the Tabernacle. They were known as the "Great Congregation." Over 3 million Hebrews/Jews were delivered by God through Moses.
When the Feast was over these new converts to Christ became known as Jewish Christians and followers of Christ. These people returned to places like Corinth, Ephesus, Philippi, Thessalonica, and even Rome. The had an experience with the Promised Holy Spirit and when they returned were the original holy-rollers and told their Jewish brethren what they experienced and learned from Peter's sermon to the twelve tribes at Jerusalem. When these Jewish Christians went to their synagogues on their Sabbath they shared and witnessed Christ, Israel's Messiah to their Jewish brethren. Many were saved in these Gentile cities and towns. But in time these Jewish Christians could not fellowship with their non-saved Jewish brethren because of the stumbling-block of Israel's Messiah being crucified on a cross and their Scripture saying anyone who is hung on a tree is cursed. They couldn't get past this fact and truth. So, these Jewish Christians began to separate from their Jewish brethren and began to gather in their homes and worship God and sing His praises.
The year of Jesus' ascension was 33 A.D. It is said that Saul was saved around 33-34 A.D. and that his first epistle was a circular letter to the Jewish churches in these various cities and towns. Paul's first epistle is dated around 54 A.D. For at least 21 years Jewish Christians were worshiping Jesus in their homes and other gathering locations. But they began to be persecuted by their Jewish brethren the Judaizers who held to the letter of the Law of Moses and were blinded by God to accept Jesus bar Joseph, their Messiah and Christ. When Paul was saved he said he went away for 17 years and went to Jerusalem for about three-four years.
In the time after Saul's conversion to Christ there was persecution in Jerusalem (Acts 8 ), and Jewish Christians left for safer and greener pastures. They met up in these cities with their Jewish Christian brethren and continued their fellowship. At this point there are no Gentiles in these Jewish Churches until Saul wrote these Jews letters explaining that there is neither Jew or Gentile, nor bond or free, neither male or female that Jewish Christians were one in Christ through the Abrahamic Covenant.
Because these Jewish Christians in these Gentile cities and towns were Hellenized by Greek culture Paul changed his name to Paul to better make himself receptive to these Hellenized Jews. To the Jew I will become a Jew that I may win the Jew he once wrote.
In Saul/Paul's travels he went to each city in these Gentile lands first to their synagogues and then to fellowship with Jewish Christians in their homes.
When he wrote to Jewish Christians in these various cities he wrote of Jewish issues and of their covenants, the promises, their practices, and the issue of Gentiles becoming saved and grafted into the natural branches which is Israel and guided his Jewish brethren in the effect Israel's Messiah had on Judaism, the covenants and the promises/prophecies of God to and for His people Israel.
I can say more and I'm sure I will.
But consider the truth of these paragraphs and understand that Jesus was sent to the lost sheep of the house of Israel. He was not sent to Gentiles. Jesus is a Jewish Messiah and the fulfillment of hundreds of years of covenant and promises and prophecies of Israel's Redeemer and King. The talk of Jesus being Israel's Messiah was fresh in the peoples minds as it was in His apostles minds for they asked Him in Acts 1 if He was going to restore the kingdom to Israel. His reply was revealing.
While the Temple stood the "ism" of Judaism remained and Christianity was founded on Israel's Messiah and He was the fulfillment of the covenants and the promises God gave to His Beloved Chosen people. The early Church until the Temple was destroyed was populated by Jews and the gospels record Jewish history with Israel's Messiah and King the central focus in the plan of God's redemption of His people. The epistles/letter written were by Jewish Christians to and for other Jewish Christians in Gentile lands for in them they record the history of the Jewish people and their religion and the covenants and promises. Saul/Paul writes to Jewish Christians at Rome:
4 Who are Israelites; to whom pertaineth the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and the promises; 5 Whose are the fathers, and of whom as concerning the flesh Christ came, who is over all, God blessed for ever. Amen.
Rom. 9:4–5.
Peter, the apostle to the Jews writes to his Jewish brethren:
4 Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust.
2 Peter 1:4.
James, an apostle to the Jews writes to Jewish Christians:
JAMES, a servant of God and of the Lord Jesus Christ, to the twelve tribes which are scattered abroad, greeting.
James 1:1.
And on through the New Testament writings.
God ordained the oracles of God be kept and possessed by the Hebrews/Jews and being the inspired writers of the New Testament being Jewish this word is kept. The New Testament writers are Jewish and wrote to Jewish Christians in the first century addressing things pertaining to the Jew first, and also later to the Gentiles.