Here is another reason I was driven to rethink how I understood the OT: Romans 4.13- “For the promise to Abraham and his descendants, that he would be heir of the world, did not come through the Law but through the righteousness of faith.” This was perhaps the key verse for my understanding of all these issues.
Just trying to understand the “righteousness of faith” in this verse already should cause you to see that the gospel of justification by faith alone is much more a part of the OT story than most people realize. But did you catch the first part of the verse? Abraham and his seed were promised to be “heir of the world.” Read Genesis 12-17 and it is clear that one of the central promises to Abraham was that he would be heir of Canaan. Abraham and his offspring were to inherit the land, but Paul translates and interprets that as inheriting the world.
This helps us to piece together Jesus saying things like “the meek shall inherit the earth” and the promise of the “new heavens and new earth” in Revelation. God’s plan from the book of Genesis was not for an ethnic people to have one piece of land, but for a spiritual people to have the whole world through/because of Christ.