I agree with this much, at least.
Christ was the promised heir of Abraham's covenant.
In Matthew 4:15-23, Christ began his ministry with the Gospel message to repent for the Kingdom of God is at hand, which was a light to the Gentiles, and the Mosaic Law was how his audience knew what sin is (Romans 3:20), so repenting from our disobedience to it is a central part of the Gospel of the Kingdom, which is in accordance with Christ being sent as the promised seed to bless us by turning us from our wickedness (Acts 3:25-26), which is the Gospel that was made known in advance to Abraham in accordance with the promise (Galatians 3:8), which he spread to those in Haran in accordance with the promise (Genesis 12:1-5).
In Genesis 18:19, God knew Abraham that he would teach his children and those of his household to walk in His way by being doers of righteousness and justice that the Lord might bring to him all that He has promised. In Genesis 26:4-5, God will multiply Abraham's children as the stars in the heaven, to his children He will give all of these lands, and through his children all of the nations of the earth shall be blessed because he heard God's voice and guarded His charge, commandments, statutes, and laws. In Deuteronomy 30:16, if the children of Abraham will love God with all of their hearts by walking in His way in obedience to His commandments, statutes, and laws, then they will live and multiply and God will bless them in the land that they go to possess. So the promise was made to Abraham and brought about because he walked in God's way in obedience to His law, he taught his children and those of his household to do that in accordance with spreading the Gospel of the Kingdom, and because they did that in obedience to the Mosaic Law. In Exodus 33:13, Moses wanted God to be gracious to him by teaching him to walk in His way that he and Israel might know Him, and in 1 Kings 2:1-3, God taught how to walk in His way through the Mosaic Law, so both Abraham and Moses spread the Gospel of the Kingdom by teaching how to walk in God's way.
Moses' covenant came later and was "added because of transgressions." It was meant to be a temporary covenant for the PUNISHMENT of Israel.
The prophet Jeremiah was already declaring the dereliction of Moses' covenant and the establishment of a "New Covenant" in the 8th century BC.
9 centuries later, some bass-ackwards Israelites were still clinging to their covenant of PUNISHMENT out of false-piety. Moses' Law gave them the opportunity to ESTABLISH THEIR OWN RIGHTEOUSNESS against that of their neighbor.
Nowhere does the Bible say either that the Mosaic Covenant was temporary or that it was a punishment for Israel, but rather it says that the Mosaic Covenant is eternal (Exodus 31:14-17, Leviticus 24:8) and that the Mosaic Law was given for our own good in order to bless us (Deuteronomy 6:24, 10:12-13). In Deuteronomy 30, it forms the basis for the New Covenant by prophesying about a time when the Israelites would return from exile, God would circumcise their hearts, and they would return to obedience to the Mosaic Law, which is what Jeremiah 31:33 and Ezekiel 36:26-27 are in regard to.
We can't establish our own righteousness even as the result of having perfect obedience to the Mosaic Law (Romans 4:1-5), so that has always been a fundmental misunderstanding of the goal of the law. In Matthew 7:23, Jesus said that he would tell those who are workers of lawlessness to depart from him because he never knew them, so the goal of the Mosaic Law is to graciously teach us how to know God and Jesus by walking in His way, which is the narrow way to eternal life (John 17:3). In Romans 9:30-10:4, the Israelites had a zeal for God but it was not based on knowing Him, so the failed to attain righteousness because they misunderstood the goal of the law by pursuing it as those righteousness were earned as the result of their works in order to establish their own rather than pursuing it as through righteousness is by faith in Christ, for knowing Christ is the goal of the law for righteousness for everyone who has faith.