Whether or not he was Shem is really immaterial. Whether or not he was a man is provided by the Hebrew writer. "Now observe how great this man was to whom Abraham, the patriarch, gave a tenth of the choicest spoils" Heb. 7:4 and since he was a man, he had a genealogy.
Satan is a spirit that has no form.He is called a
man of sin .It is how the Holy Spirit uses the word man. When used it does not mean it is literally a man. The influence whether good or evil can be compared to as
if he was a man
1Ti 2:5 For there is one God, and one mediator between God and men,
the man Christ Jesus;
Hebrew 7 is not confirming a genealogy but just the opposite. No mother or father… no genealogy
Shem is a creature not the Creator. God is not a man as us.
He was typified as man appearing as a theophany, a vision. (No corruptible flesh) which he did appear
as if he had form at other times. But when he came to put away sin in the flesh a theophany or a vision would not work out.
Rom 8:3 For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of
sinful flesh, and for sin, condemned sin in the flesh: