Shem is the son of Noah associated with the genealogy leading to Abraham in Genesis.
After the Flood, Genesis 10 presents genealogies for Noah’s sons: Japheth, Ham, and Shem. Genesis 11 then follows Shem’s line in detail, naming successive descendants until it reaches Terah, the father of Abram, later known as Abraham. This genealogical transition is why Shem is the relevant answer.
The passage is not saying that Shem was Abraham’s immediate father. Several generations separate them. Genesis 11:10 begins a sequence from Shem to Arpachshad, Shelah, Eber, Peleg, Reu, Serug, Nahor, and Terah before Abram is introduced.
This is distinct from the later meanings attached to “Semitic,” a term derived from Shem’s name. Biblical genealogies, linguistic classifications, and modern population history are related only indirectly, so they should not be treated as identical systems of classification.