Why does it start with the Nation of Israel ? Because the creator chose it that way and it is undeniable and unalienable.
And there came one that had escaped, and told Abram the Hebrew; for he dwelt in the plain of Mamre the Amorite, brother of Eshcol, and brother of Aner: and these were confederate with Abram.
Gen 17:1 -2
And when Abram was ninety years old and nine, the LORD appeared to Abram and said unto him, I am the Almighty God; walk before me, and be thou perfect.
And I will make my covenant between me and thee and will multiply thee exceedingly.
And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him.
Read Gen 25th Chapter & Gen 49th Chapter
This continues the lineage of Abraham to Isaac to Jacob to the 12 Tribes of Israel that was promised to Abraham in Genesis 17th Chapter.