I agree that understanding who a law was given to matters, but we need to understand that the Law was not given as instructions for how to live as a Jew, but rather it was given as instructions to His followers for how to walk in His ways, and as followers of God we should seek to walk in His ways.
I agree that the Law was only given to Israel, but it was never intended only for Jews, but rather the Jews were given the role of being a light to the nations, of blessing them by teaching them how to walk in God's ways in obedience to His Law (Isaiah 2:2-3, Isaiah 49:6, Deuteronomy 4:5-8). In Exodus 12:38, there was a mixed multitude that went up out of Egypt with them and in Joshua 8:33, Israel was inclusive of both the foreigner and the native born. In Acts 15:16-17, they certainly saw themselves as being the restoration of Israel in fulfillment of prophecy rather than as a brand new entity that was distinct from Israel. In Romans 9:6-8, Israel is not made up of those who are descended from Israel, but of those who have faith in the promise. In Ephesians 2:19, through faith in Messiah, Gentiles are no longer strangers or aliens, but are fellow citizens of Israel along with the saints in the household of God. In 1 Peter 2:9-10, Gentiles are now included among God's chosen people, a holy nation, a royal priesthood, and a treasure of God's own possession, which are all terms used to describe Israel, so Gentiles now have the privilege and the delight of getting to obey the instructions that God gave to Israel for how to fulfill those roles. However, if you want to be a stickler about what was only given to Israel, then in Jeremiah 31:31, the New Covenant was only made with the house of Judah and the house of Israel, so it is only through faith in Messiah that Gentiles are able to join Israel and partake of the New Covenant.