If your referring to the 10C or Noahide Laws, I would agree. I Believe that God leaves no one out and has extended revelation to all one way or another. If not He would not be the God of the bible, but a vain imagination of men.
I agree about bloodline. I understand where you get "conversion or convert to the Law", but I see something different.
Through Moses came the law. Why the law? What does law do? Law demonstrates the "Holiness of God" as compared to "Favor [grace] and Truth". The nation would say,"What nation has such just laws like Israel?". Which points to the God who gave them. Holiness is special or set aside for special use. I see Israel being a witness to the world about God's righteousness. Jesus came to demonstrate God's Love [Favor\grace] and Truth toward all mankind.
I do not separate the "10C" from the rest of the commands. That is more something modern, and a dividing line that I do not see within Scripture. The Law is five books.
If you read the names of those going to battle as Israelite warriors and mighty men, you will notice that many (actually most) of the names mentioned are actually from tribes outside of the twelve. To me, this sets the standard, that the Law reached beyond the bounds of heredity and genetics.
The Word gives us examples of three types of revelation. The Natural (Creation and the effects of Creation), the written Word (divided between the Law and the Prophets), and the Living Word (divided between the words of Christ, and the Spirit that opens up the rest of Scripture to us).
All men know there is a God,
even if they make excuses and deny it.
They have seen Creation, and have felt it's effects.
All those who have read the Word, even in part, know that they are sinners, and that there is a Redeemed,
even if they make excuses and deny it.
They have borne witness to the words of God, and have felt it's convicting power.
Those who have experience Christ know that He is the One,
even if they faulter and come upon doubt,
because they have seen the Light, and can no longer hide.
You began to get into the Law, and how it displays God's holiness. But this is only one of the many things it displays.
As for Israel, it is not one nation, but two. It is physical AND spiritual.
Not all members of the physical are part of the spiritual, or else why did God choose one brother over the other? Born of the same father, born of the same mother, yet "Jacob have I loved".
The Israel that bore witness was the spiritual. The physical ALWAYS rebelled.
The testimony of physical Israel is one of a just God, who punishes those who rebel against Him. The testimony of physical Israel is not one of hope, but of assured justice without favoritism.
It is by the testimony of spiritual Israel that there is hope. And it is of THIS nation to which we have been brought near and made citizens, through our unity with Christ.