Something to point out that I think flies by alot of people is where it says Ruth was a moabitess.

If you look later on in Ruth it talks about boaz doing the part of a kinsman and raising up an inheritance for her.

This law applied to Israelites not moabites. One should conclude that Ruth was infact Israelite in decent that was called a moabite due to her living in that land. Same as one would be called an American because I live in this country even if they moved from a different country.