Shem is traditionally regarded as the ancestor of the Hebrews in the genealogies after Noah.
Genesis names Shem, Ham, and Japheth as Noah's sons. Genesis 11 traces a line from Shem through successive generations to Terah, the father of Abram, later called Abraham. Because this genealogy leads to Abraham, Shem is associated with the ancestry of the Hebrew patriarchs.
The term “Semitic” was later formed from Shem's name and became a linguistic and cultural label connected with peoples speaking Semitic languages. That later scholarly term is broader than the biblical genealogy and should not be treated as a simple biological classification of every modern group called Semitic.
Genesis also includes the episode in which Noah's reaction to Ham leads to a pronouncement involving Canaan, while Shem and Japheth receive different treatment. These details are separate from the genealogy. For the ancestry question, the relevant chain is Shem to Abraham in Genesis 11.