'First born' in the Bible

And again, when God sent the Firstborn One [i.e., Jesus. See Rom. 8:29; Col. 1:15, 18; Rev. 1:5] into the world, He said [Deut. 32:43 LXX], "And all of God's angels should worship Him."

By [having] faith, he established the Passover Festival [Note: This festival was first celebrated in Egypt by the fleeing Israelites, then observed annually in commemoration of that event], and had [lambs'] blood sprinkled [on the door jambs] to prevent the one who destroyed the firstborn children from touching them. [See Ex. 12:23].

and that no one becomes immoral or ungodly, like Esau, who sold his right to the firstborn son's inheritance for a single meal.

and to the church of the firstborn ones [i.e., those who have received an inheritance from their Father], whose names are recorded in heaven. [See Luke 10:20]. [You have come] to God, who is the Judge of all people, and to the spirits of righteous people who have become [morally] perfect [i.e., that great company of God's people who have gone on to their heavenly reward],