Also it helps to view the book of Hebrews as a divinely inspired commentary on:
Jeremiah 31:31 Behold, the days come, saith the LORD, that I will make a new covenant with the house of Israel, and with the house of Judah: 32 Not according to the covenant that I made with their fathers in the day that I took them by the hand to bring them out of the land of Egypt; which my covenant they brake, although I was an husband unto them, saith the LORD: 33 But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people. 34 And they shall teach no more every man his neighbour, and every man his brother, saying, Know the LORD: for they shall all know me, from the least of them unto the greatest of them, saith the LORD: for I will forgive their iniquity, and I will remember their sin no more.
Jeremiah 31:31-34 is essentially the Gospel prophetically placed in the Old Testament.
Hebrews is a book written to the Hebrews telling the Hebrews to stop being Old Covenant Hebrews and to become New Covenant Hebrews because God has moved on from the Old Hebrew Covenant to the New Hebrew Covenant.**
**John 4:22, Romans 2:28-29, Romans 9:6-13, Philippians 3:3
Galatians 3:24 Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith. 25 But after that faith is come, we are no longer under a schoolmaster.
Romans 3:31 Do we, then, nullify the law by this faith? Not at all! Rather, we uphold the law.