Ruth is the perfect proof for typology. It shows that typology is necessary to biblical interpretation. Observing the text of Ruth only from a grammatical perspective misses all sorts of treasures. The positive aspect of typology is that it is not hidden, but it is all over the place. The Spirit does not waster his breath. Ruth is a fine example of this. Ruth is Israel in sin and Israel restored. Naomi is Israel unrepentant and Ruth is Israel clinging to God. The difficulty–and I should add the common distaste of biblical typology–in this form of hermeneutic is that it demands biblical knowledge. It demands knowing biblical history and it demands broadening your view of redemptive history. Redemption is the maturation of history. In Christ, the pieces, facts, details of the Bible come together. No longer will you be able to look at Genesis 1 without realizing its vast implications to the rest of sacred revelation.
Ruth does just that. It exposes us to laws in the Mosaic literature (Levirate Laws), to marriage themes (such as the union/clinging of Adam and Eve in Genesis 2), and to how eschatology functions (Israel exiled, Israel restored). Ruth is gospel, but it is just one of many pictures given to us in miniature form through Scriptures.