What’s Up With the Title?
Books in the Bible get their names all different ways. Some are named after the people who wrote them (Matthew, Mark, Luke, and John). Some titles come from the first line of the story (like Genesis and Revelation). The Book of Ruth, which is usually just called Ruth, gets its title from its main character. This is Ruth's story and it's her name up on the marquee.
Over the years, some scholars have argued that Ruth is actually more focused on Naomi than the titular heroine. After all, it's Naomi's family and her loss that run throughout the story. But, since Naomi doesn't do anything besides feel bad for herself and set her daughter-in-law up on dates, it's Ruth who gets the glory in the end.