This arrangement accurately captures this melody popular fiddle tune. For several parts of the main melody you'll use your thumb to fret notes on your 5th string by wrapping it over the neck. This was a trick used by Earl Scruggs in his lead and especially in his backup. Using the Thumb to fret notes will open a lot of new ways to play in the melodic style that would sometimes be tricky when just using your fingers. Both techniques are valid and should be explored.