There are many songs sung by different characters at various occasions in the book. I normally skip them since I found they normally don't tell more about the story and to be honest I don't quite enjoy them as a second language speaker of English. My understanding is in Middle Earth, people use songs to document or/and pass on knowledge and histories. So they should be indispensable to the world Tolkien created for us.
How do they contribute to the development of the story? Is this a common of way telling ancient stories in English literature?