'First born' in the Bible

But Abel brought [an offering of] the [finest] firstborn of his flock and the fat portions. And the Lord had respect (regard) for Abel and for his offering;

Canaan became the father of Sidon, his firstborn, and Heth

After Terah had lived seventy years, he became the father of Abram and Nahor and Haran [his firstborn].

Then the next day, the firstborn said to the younger, “Behold, I lay with my father last night; let us make him drunk with wine tonight also, and then you go in and lie with him, so that we may preserve our family through our father.”

Uz the firstborn and Buz his brother and Kemuel the father of Aram,

and these are the names of the [twelve] sons of Ishmael, named in the order of their births: Nebaioth, the firstborn of Ishmael, and Kedar, Adbeel, Mibsam,

Jacob answered, “First sell me your birthright (the rights of a firstborn).”

and make me a savory and delicious dish [of meat], the kind I love, and bring it to me to eat, so that my soul may bless you [as my firstborn son] before I die.”

Jacob said to his father, “I am Esau your firstborn; I have done what you told me to do. Now please, sit up and eat some of my game, so that you may bless me.”

Isaac his father said to him, “Who are you?” And he replied, “I am your son, your firstborn, Esau.”

The sons of Leah: Reuben, Jacob’s firstborn, then Simeon, Levi, Judah, Issachar, and Zebulun;

These are the tribal chiefs of the sons of Esau: The sons of Eliphaz, the firstborn of Esau: Chiefs Teman, Omar, Zepho, Kenaz,

Now Judah took a wife for Er his firstborn; her name was Tamar.

But Er, Judah’s firstborn, was evil in the sight of the Lord, and the Lord killed him [in judgment].

Joseph named the firstborn Manasseh (causing to forget), for he said, “God has made me forget all my trouble and hardship and all [the sorrow of the loss of] my father’s household.”

Now these are the names of the sons of Israel, Jacob and his sons, who went to Egypt: Reuben, Jacob’s firstborn.

But Israel reached out his right hand and laid it on the head of Ephraim, who was the younger, and his left hand on Manasseh’s head, crossing his hands [intentionally], even though Manasseh was the firstborn.

Joseph said to his father, “Not so, my father, for this is the firstborn; place your right hand on Manasseh’s head.”

“Reuben, you are my firstborn;My might, the beginning of my strength and vigor,Preeminent in dignity and preeminent in power [that should have been your birthright].

“But unstable and reckless and boiling over like water [in sinful lust], you shall not excel or have the preeminence [of the firstborn],Because you went up to your father’s bed [with Bilhah];You defiled it—he went up to my couch.