Ruth, a heathen woman by origin, managed to become a part of God's people, entirely based on God's mercy and grace, which He showed her through people like Naomi and Boaz.

Naomi's role was more like God the Father, because she took Ruth under her wings and protected her all the way since her "conversion". Naomi was so to speak the orchestrator of every good thing for Ruth.

Boaz, on the other hand, is a perfect representation of Jesus as the Kinsman Redeemer (Ruth 4:1-12). He was the one that "bought" Ruth with a price, redeeming her from her heathen background and providing for her a place in God's family and even, we can see later that the Lord chose her to be one of the forefathers (or rather foremothers) of King David (Ruth 4:18-22).