What is the biblical basis for thinking God established the principle of birthright and inheritance

As this question is not concerned with establishing a ‘secular’ answer about the origins of the idea of birth-right (which includes inheritance) I can breathe a sigh of relief and concentrate on collating various Old Testament scriptures that give information on where human and divine views digress. Therein lies the answer to the question, as to whether or not God was the origin of a concept like inheritance.

I suggest that, from the Bible texts I have studied, it can be said that God’s concept of ‘inheritance’ differs radically from human concepts at some critically important points. Take Psalm 2, for instance. This is a prophetic statement about the Lord God and his Anointed One. Without offering any interpretations, I simply point out that verse 8 has God invite his Son to “Ask of me, and I will make the nations your inheritance, the ends of the earth your possession.” This is where the inherited rule of the Lord’s Anointed becomes the rule of God himself, for to submit to the rule of the Anointed is to “Serve the LORD” God (vs. 11).

Working backwards now, from the greater to the lesser, Bible texts show where God breaks through into what humans considered to be the right of the first-born and his (and it’s usually a ‘his’) inheritance. God keeps asserting his sovereign right to stop humans doing what they would choose to do regarding this birth-right principle.

You have already mentioned examples of this, including Abraham’s miracle child, Isaac, and the twins, Esau and Jacob. The youngest son of Jacob was chosen by God as ‘over’ his 11 brothers. God sent dreams to the lad, Joseph, foretelling this in symbolic imagery; decades later, it came to pass, even his aged father realising it. Jacob blessed Joseph’s second-born son above the first-born son, putting Ephraim ahead of Manasseh. Jacob did not bless his firstborn, Reuben, but said he would no longer excel, then pronounced Joseph ‘prince among his brothers’ (Genesis chapter 48 to 49:1-26).

The daughters of Zelophehad were chosen to inherit (when they stood up and made a legal case for it) due to their father having no sons. Numbers ch. 27 & 36:1-12. Deuteronomy 21:15-17 details the rights of the firstborn (not always the first-born son – a first-born daughter with no brothers could inherit, due to the precedent of Zelophehad’s daughters.)

The youngest son of Jesse was chosen by God as king ‘over’ his many brothers and the nation (1 Samuel 16:1-13). No doubt there are lots of other cases; this is just a sample to show that God’s choosing is not determined by human customs, or even laws. Perhaps that’s because God’s law states that all humans have inherited sin from our original, earthly father, and that “the wages of sin is death” (Romans 5:12 & 6:23). That’s the horrible inheritance we all get and which we need to face up to. Any earthly inheritance is just so much of a soon-to-be rust-bucket heaped full of moth-eaten fabric.

But if God should call us his ‘sons’, adopting us into his heavenly family (Romans chapter 8), then our inheritance is beyond our wildest dreams, kept in heaven for us. Nor is such an inheritance due to any merit or standing on our part, but a freely bestowed gift of grace. Though we be the first-born son of an earthly king or the poorest girl in the gutter, humanly speaking, God elevates those he chooses.

This, to me, indicates that while there may be something of the divine principle of sonship and inheritance in human primogeniture laws, human laws are (as so often is the case) too rigid and short-sighted to grasp the spiritual principles that ought to be their basis.