Could the law help a Jew become a law keeper?
No. The law had no power to help even the Jew be a law keeper. It could do nothing but condemn and give the knowledge or awareness of sin. Paul writes that by the deeds of the law no flesh shall be justified in God's sight, because law-keeping cannot produce righteousness.
Les explains that the law's purpose was never to empower obedience but to expose sin. Even for the Jew, the law had no power to help him be a law keeper; it could only condemn him and bring the knowledge or awareness of sin. Paul wrote that by the deeds or keeping of the law shall no flesh be justified in God's sight. The law can do nothing but point the finger and say, 'You're guilty.' But the flip side is the righteousness of God without the law—not human righteousness, which is like filthy rags, but God's righteousness apart from law.
Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.