Why did Israel have no concept of going to heaven when they died?
Israel had no concept of dying and going to heaven because they were God's earthly people, with all their promises being earthly, not heavenly. They only saw the grave and, if they believed in a hereafter, expected an earthly kingdom promised to Abraham, Isaac, and Jacob. They were not supposed to have a heavenly hope.
Les explains that all the way up through the Old Testament, Israel were God's earthly people, and their promises were earthly. They had no concept of dying and going to heaven. They only saw the grave. Many did not believe in life hereafter; those who did saw only a kingdom on this earth, which had been promised to Abraham, Isaac, and Jacob. They never had a concept of dying and going up to heaven, and they weren't supposed to, because they were an earthly people. Les contrasts this with the church age, where there is a great difference.