I found an interesting answer by Scott Hahn that says Shem is Malchizadek. I’d have made a link but I’m new and can’t figure out the tutorial. SOME ONE HELP!
salvationhistory.com/
God promises to bless Abraham. And we know that those blessings come in his descendants, especially in Jesus. But during the course of Genesis, the only actual blessing that Abraham receives is from the mysterious king-priest, Melchizedek (see Genesis 14:18-20).
We have to do a little background, and even a little math, to understand what that’s all about.
Shem receives a cosmic blessing from Noah - “Blessed be the Lord, the God of Shem!” - which marks the first time in Scripture that God is identified with any one human being (see Genesis 9:26-27). God is designated as “the God of Shem” - a sign of Shem’s great righteousness and stature before God.
However, then Shem disappears. Unlike the other first-borns - Adam, Cain, Noah - we don’t see him fall into disgrace. In fact, we don’t hear anything more about him - except that he has sons and that ten generations later one of his descendants, Terah, gives birth to three sons, the first-born of which is Abraham (see Genesis 11:26-27). It is very curious, though, that we never see Shem - heralded as the most righteous of the men born after the Flood - handing on his blessing to his first-born or to any one of his children.
This is where the math comes in: Add up the numbers given in the account of the descendants of Shem’s line (see Genesis 11:10-26): Abraham is born 290 years after Shem’s first-born, Arpachshad. Now, if Shem is 100 years old when Arpachshad is born, that means that he’s 390 when Abraham is born. And, if Shem lived five hundred years after Arpachshad’s birth, and Abraham lived to be 175 years old (see Genesis 25:7), that means that Shem outlived Abraham by 35 years.
Who cares? Why does it matter? Well, for the ancient rabbis and for centuries of early Christian interpreters, including probably the author of the Letter to Hebrews, it mattered a great deal. It’s also the key to figuring out what’s happening between Abraham and Melchizedek in Genesis 14.
According to a long tradition - Jewish and Christian - the mysterious Melchizedek is actually Shem, the great patriarch, the righteous inheritor of the blessings promised by God after the Flood.