Shem is named first in the ark account’s family list.
Genesis 7:13 lists Noah’s sons as Shem, Ham, and Japheth when they enter the ark with their wives. The same three names recur throughout the flood narrative and its aftermath. Canaan, by contrast, is identified later as a descendant of Ham, not as one of Noah’s sons.
The order of names in a biblical list does not always establish a person’s age, and Genesis contains other passages where the ordering of Noah’s sons is discussed or interpreted differently. This question asks only which name appears first in the entry list. Shem later becomes the ancestor associated with the “Semitic” name in traditional genealogical terminology.