Was the Old Testament period mainly God dealing with Israel?
Yes. The period from Genesis 1 until the conversion of Saul of Tarsus was predominantly God dealing with Israel, and that's obvious. Most of the Bible was written for the nation of Israel, while Romans through Philemon are specifically for us.
Les explains that everything from Genesis 1 up until the conversion of Saul of Tarsus is predominantly God dealing with Israel. After Israel continued to reject the crucifixion of Christ, God raised up Paul as the Apostle of the Gentiles and spokesman for God during this period. Les also points out that most of the Bible is really written for the nation of Israel, and not everything the Bible says is for us. He gives Leviticus 5 as an example and says what is for us is confined to Romans through Hebrews, though even Hebrews is written primarily to Jews, so Romans through Philemon.