Shem is traditionally listed first among Noah’s sons in Genesis after the Flood.
Genesis 9:18 names Shem, Ham, and Japheth as Noah’s sons who came out of the Ark. Genesis then develops their descendants in the genealogical material that follows. Shem is especially important in the biblical family line because Genesis 11 traces a genealogy from Shem to Abram, later called Abraham.
The order of names does not mean that every interpretive tradition treats Shem as the oldest. Genesis 10:21 has wording that has generated different translations and discussions about the relative ages of Shem and Japheth. For a straightforward identification question, however, Shem is the son named first in the post-Flood list.
Canaan is not one of Noah’s sons; Genesis identifies him as Ham’s son. That makes Canaan a common but incorrect option when the family relationships are remembered only generally. Shem, Ham, and Japheth are the three sons associated directly with Noah in the Ark account.