The audience of the Gospels was centered on the lost sheep of the house of Israel and the preaching of the Kingdom was the message.
Rom 3:1 What advantage then hath the Jew? or what profit is there of circumcision?
Rom 3:2 Much every way: chiefly, because that unto them were committed the oracles of God.
The Jews had the advantage over the Gentiles for the word of God was given to them, the Old Testament.
Rom 1:17 For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith.
God's Wrath on Unrighteousness
Rom 1:18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness;
Rom 1:19 Because that which may be known of God is manifest in them; for God hath shewed it unto them.
Rom 1:20 For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse.
Creation testifies of a God, and of His attributes, which one of them is love, for He provided food, and the means to make clothing, and shelter, and is the universal law for everyone through the history of mankind, and covers the 2 greatest laws, love God, and love people, which is how a saint is saved.
Isa 49:6 And he said, It is a light thing that thou shouldest be my servant to raise up the tribes of Jacob, and to restore the preserved of Israel: I will also give thee for a light to the Gentiles, that thou mayest be my salvation unto the end of the earth.
Mat 15:24 But he answered and said, I am not sent but unto the lost sheep of the house of Israel.
Luk 24:46 And said unto them, Thus it is written, and thus it behoved Christ to suffer, and to rise from the dead the third day:
Luk 24:47 And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem.
Joh 10:15 As the Father knoweth me, even so know I the Father: and I lay down my life for the sheep.
Joh 10:16 And other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd.
Mat 28:19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:
Mat 28:20 Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.
Rom 1:16 For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.
Rom 10:11 For the scripture saith, Whosoever believeth on him shall not be ashamed.
Rom 10:12 For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon him.
Act 10:34 Then Peter opened his mouth, and said, Of a truth I perceive that God is no respecter of persons:
Act 10:35 But in every nation he that feareth him, and worketh righteousness, is accepted with him.
Eph 2:11 Wherefore remember, that ye being in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands;
Eph 2:12 That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:
Eph 2:13 But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.
Eph 2:18 For through him we both have access by one Spirit unto the Father.
Eph 2:19 Now therefore ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household of God.
Jesus was only sent to the lost sheep of Israel, for they had to hear it first, and then it spread from there out to the nations.
The Gospels are for everyone for Jesus said to the disciples go out in to all nations, and teach them before Paul was even a Christian and went to the Gentiles.
The Gospels were given to all people to the Jew first, and then the Gentile, but it was already written in the Old Testament that salvation through the Savior would go to the Gentiles, as well as the Jews.