So you agree that the "church" and body of Christ in Ephesians 5:23 are the same?
The gathering of God's people (Church) prior to the new covenant mainly consisted of those from the nation of Israel. However, There were proselytes from other nations who converted as you stated.
Under the new covenant, this gathering of God's people is called the body of Christ and is composed of Jews and Gentiles.
Ephesians 2:14-16 For He Himself is our peace,
who has made the two one and has torn down the dividing wall of hostility by abolishing in His flesh the law of commandments and decrees. He did this to create in Himself one new man out of the two,
thus making peace and reconciling both of them to God in one body through the cross, by which He extinguished their hostility.
Galatians 3:28-29 There is neither Jew nor Greek, slave nor free, male nor female,
for you are all one in Christ Jesus.
And if you belong to Christ, then you are Abraham’s seed and heirs according to the promise.
Acts 10:34-36 Then Peter began to speak: “
I now truly understand that God does not show favoritism,
but welcomes those from every nation who fear Him and do what is right. He has sent this message to the people of Israel, proclaiming the gospel of peace through Jesus Christ, who is Lord of all.
Ephesians 5:23 For the husband is the head of the wife even as
Christ is the head of the church, his body, and is himself its Savior.
Are God's people those of the old covenant or those of the new covenant?
Romans 7:4 Likewise, my brothers,
you also have died to the law through the body of Christ, so that you may belong to another, to him who has been raised from the dead, in order that we may bear fruit for God.
Hebrews 8:13 In speaking of a new covenant,
he makes the first one obsolete. And what is becoming obsolete and growing old is ready to vanish away
Galatians 4:30-31 But what does the Scripture say? “Cast out the slave woman and her son,
for the son of the slave woman shall not inherit with the son of the free woman.”
31So, brothers, we are not children of the slave but of the free woman.