Shem is traditionally identified as the ancestor associated with the Semitic peoples in the biblical genealogical tradition.
Genesis 10 presents the descendants of Noah's three sons—Shem, Ham, and Japheth—as the peoples distributed across the post-Flood world. Shem's line includes figures such as Arpachshad, Eber, and Terah, and it leads into the genealogy of Abraham.
The term “Semitic” was later formed from Shem's name and became a linguistic and ethnographic label. In modern scholarship, Semitic primarily describes a language family, including Hebrew, Arabic, Aramaic, and Akkadian, rather than proving a single biological ancestry for all speakers.
This question concerns the traditional biblical association, not a modern genetic classification. Canaan is listed among Ham's descendants in Genesis 10, while Japheth's line is presented separately.