The children of Israel in the Bible are simply the descendants of Jacob. The term children of Israel emphasizes the lineage of the Hebrew people as being through the patriarch Jacob. The children of Israel are also called Israelites.
It all started with God’s promise of a family—a big family—to a childless couple, Abraham and Sarah (Genesis 11:30; 12:1–3). God miraculously provided a son, Isaac, to fulfill the promise (Genesis 21:3), and He repeated the father’s promise to the son (Genesis 21:12; 26:3–4). Isaac married Rebekah, and they were childless, too, until God intervened and provided a son, Jacob, to continue the promise (Genesis 25:26). God then reaffirmed the Abrahamic Covenant with Jacob (Genesis 28:14–15). Later, God changed Jacob’s name to Israel (Genesis 35:10). Jacob/Israel had twelve sons who carried on the family line; each son’s descendants formed a particular tribe of Israel, and all the descendants of Jacob were collectively called the children of Israel.
Children of Israel became the most common term for the Israelites in the Bible. Its use is a constant reminder of the faithfulness and power of God. The Lord who formed the nation of Israel has been faithful to keep His promises to the sons of Abraham, Isaac, and Jacob, and His great power has been on display throughout their history.