Let's see how your theory works. Substitute "gentiles" for "you" and "Jews" for "us":Seriously? You havent shown one iota of evidence that your claims are correct. Anyone reading the passage in context can see that your claim is simply wrong.
1 Paul, an apostle of Christ Jesus by the will of God,
To God’s holy people (Jews) in Ephesus, the faithful in Christ Jesus:
2 Grace and peace to the gentiles from God the Jews' Father and the Lord Jesus Christ.
Praise for Spiritual Blessings in Christ3 Praise be to the God and Father of the Jews' Lord Jesus Christ, who has blessed the Jews in the heavenly realms with every spiritual blessing in Christ. 4 For he chose the Jews in him before the creation of the world to be holy and blameless in his sight. In love 5 he predestined the Jews for adoption to sonship through Jesus Christ, in accordance with his pleasure and will— 6 to the praise of his glorious grace, which he has freely given the Jews in the One he loves. 7 In him the Jews have redemption through his blood, the forgiveness of sins, in accordance with the riches of God’s grace 8 that he lavished on the Jews. With all wisdom and understanding, 9 he made known to the Jews the mystery of his will according to his good pleasure, which he purposed in Christ, 10 to be put into effect when the times reach their fulfillment—to bring unity to all things in heaven and on earth under Christ.
11 In him the Jews were also chosen, having been predestined according to the plan of him who works out everything in conformity with the purpose of his will, 12 in order that the Jews, who were the first to put the Jews' hope in Christ, might be for the praise of his glory. 13 And the gentiles also were included in Christ when the gentiles heard the message of truth, the gospel of the gentiles' salvation. When the gentiles believed, the gentiles were marked in him with a seal, the promised Holy Spirit, 14 who is a deposit guaranteeing the Jews' inheritance until the redemption of those who are God’s possession—to the praise of his glory.
If you read it carefully, it's nonsense!
The only nuance is "we who were the first to put our hope in Christ," meaning all Jesus' disciples who followed Him when He was alive. So when he says "you," he is talking about those he is writing to, the church in Ephesus, which consisted of both Jews and gentiles. They weren't "the first to hope in Christ" because they were converted more than a decade later.
But all the "us"es and "we"s are talking about the universal church, which are "God's holy people," and those "in Ephesus" are part of it. Just because he is writing to a specific church, doesn't mean those are the only people this epistle applies to. Paul expected (as he wrote elsewhere) that the epistle would be circulated to all the churches. Therefore, Paul was meaning that the "us" and "we" in this context applied to all various groups of Christians.
If what you claim is true, then gentiles aren't saved until they become Jews. But the fact that he says "when YOU believed, YOU were marked with a seal, the promised Holy Spirit, who is a deposit guaranteeing OUR inheritance..."
means that Paul is including the "you" with "us" in the inheritance. To claim otherwise is nonsense.
IMO you need to scrap your theory and properly exegete the context.