Paul taught that the Law ended when Jesus came and also that Jesus himself ended the Law (Ephesians 2:14-15, Romans 10:4, Galatians 3:24-25). In teaching that the Law of God had come to an end, he was essentially preaching lawlessness, i.e., anarchy.
But the Hebrew scriptures say something else:
“…and all His commandments are trustworthy. They are forever true, to be obeyed faithfully and with integrity” (Psalms 111:7-8)
“All your words are true; all your righteous laws are eternal” (Psalms 119:160)
Paul also taught that a person cannot be justified or deemed righteous by keeping the Law of God (Galatians 3:11, Galatians 2:16, Romans 3:20).
But the Hebrew scriptures teach the exact opposite. It says men who keep the Law are righteous. (Ezekiel 18:9, Psalm 119:1, Deuteronomy 6:25)
Paul taught that if one is led by the Holy spirit, he is not under the Law.
“But if you are led by the Spirit, you are not under the law” (Galatians 5:18)
But the Hebrew scriptures teach the exact opposite. It says in Ezekiel 36:27 that having the Spirit moves people to follow the Law.
“And I will put my Spirit in you and move you to follow my decrees and be careful to keep my laws” (Ezekiel 36:27)
You say "The ONLY scriptures Paul had to work with were from the Hebrew scriptures", but Paul's own words and teachings reveal he was unaware of what the Hebrew scriptures taught about the Law. Either that, or he was deliberately distorting Hebrew scriptures.
The Law teaches that from the very beginning of creation two powers were placed over two Adams. One power, namely, Jehova, rules the Adam formed of earth cursed by Jehova whereas the other power, namely, the holy spirit, rules the Adam who lives forever made in the image of the Holy Spirit.
What the TOR and Paul understood from that was no matter what a human does, he will die because Jehova has cursed the ground or earth which forms the body. IOW, Jehova is the god of THIS material world. It has been that way since the beginning even before the Mosaic Law, therefore the Mosaic Law changes nothing except to confirm the existence of our fallen material nature and condemn it.
We would be without hope except the Most High God sent another power, namely, the holy spirit, to create a second Adam who lives forever. The Holy Spirit forms a moral conscience in the second Adam. The second Adam is spiritual made in the image of the Holy Spirit, perfected, holy, and righteous.
The TOR and Paul understand that Jehova has no authority over the second Adam created by the Holy Spirit, and the Holy Spirit has no authority over the material body formed by Jehova. It is why good people still die because their material bodies are cursed by Jehova. But souls surrendered to the Holy Spirit, sealed to the Holy Spirit, married to the Holy Spirit, live forever because they belong to the second Adam.
Moreover, the Holy Spirit could care less if the mortal Adam removes his foreskin or what food he puts in his mouth or how far he walks on the sabbath because those purity requirements put in place by Jehova ONLY only apply to the material body. The Holy Spirit only cares about the inside of man, to perfect his conscience for doing right. It is why for the second Adam the whole Law can be summarized into one commandment, love your neighbor as yourself. It is why the eternal life given to second Adam is universally available irregardless of race, nationality, sex, or wealth. The moral conscious formed by the holy spirit is an absolute religion available to everyone. Jewish particularism provides no additional benefit.
This is what Paul was trying to demonstrate to the Jews and they were not having it and still do not get it. The only reason the Mosaic Law is considered holy by the TOR, the prophets, and Paul is for its allegorical meaning, its symbolism, its types, its figures, REVEALING the economy of salvation willed by the God Most High. Its literal meaning holds no efficacy for salvation. For example, the literal meaning of the creation myths is useless. But in the hands of a prophet, priest, or seer, it reveals the plan of the Most High God for humanity, for Adam.
So reconsider what Paul is saying in the quotes that you gave above in light of the two powers creating the two Adams in the beginning. Jehova‘s power and authority is limited to rule the mortal Adam, whereas, the Holy Spirit‘s power and authority is over the second or spiritual Adam who lives forever.
Which one would you rather be, the mortal Adam serving Jehova, or the spiritual Adam serving the Holy Spirit? Which Law would you rather keep, the literal, earthly meaning of the Law or its spiritual, allegorical, eternal meaning of the Law? Which covenant would you rather belong to, the Mosaic covenant by the letter written in stone, or the New covenant written on our hearts?
The Tor’s and Paul’s whole point was that as long as Jews remain focused on the outward requirements of the Law, eg., circumcision, food purity, sabbaths, etc., then they are missing the more important inner requirements of the Law, eg., a moral conscious, which is the ideal, spiritual worship of the Most High God.
One final note: The TOR did say it was beneficial to follow some requirements of the Mosaic Law, most likely for its symbolic meaning. He never says ritual purity is efficacious for salvation. Paul just takes his message to its logical conclusion, that for Gentiles, the only thing that actually matters is a moral conscious formed by the Holy Spirit, namely, the inner Yeshua.