Moses refers to him frequently as the father of the sons of Eber at the outset of the comprehensive lineage of Shem, indicating a transition from the broader narrative to the specific history of the sons of Eber, or, in essence, the Jewish people.
He is noted as the elder sibling of Japheth. The Hebrew can also convey the meaning of brother to Japheth the elder. However, in this context, the language suggests it would be more appropriate to elaborate, for instance, by stating the eldest son of Noah. The implication that Japheth is the firstborn can be drawn through an analysis of the chronological accounts of Noah's life alongside that of Shem (Gen. 5:32, Gen. 7:11, Gen. 11:10). It is possible that in the initial reference, a rounded number is used in place of a more exact figure, similar to how the three sons are mentioned without specifying their birth order; thus, the details of chronology are clarified in the subsequent instances. On the other hand, it is clear that Shem is regarded as the firstborn since he is typically listed first in the enumeration of the siblings (Gen. 5:32, Gen. 6:10, Gen. 7:13, Gen. 9:18, 23, Gen. 10:1). By diverging from this customary sequence and presenting Shem's lineage after that of his brothers, the author intended to emphasize that Shem is indeed the elder sibling of Japheth, whose lineage is introduced before the others, while the third brother is excluded from their mention, having already been distanced from them both by temperament and curse.