Watch the Level 4: Beginner Classical online guitar lesson by Andrew Leonard from Take 5: Beginner Classical
In the Baroque era, the use of counterpoint was part of most compositions. Counterpoint is the art of writing two (or more) notes to be played at the same time that sound good together yet have their own independent melody. Simply put, you're not thinking of "melody and accompaniment" as you did in "Greensleeves", Vivaldi's "Largo in D" or "Kemp's Jig."
The bass line of this piece does accompany the melody, but it's also interesting to play and listen to on its own. If you want to hear counterpoint taken to its extremes, search the internet for "Bach five voice fugue."
Fugue is the compositional form which allowed composers to showcase their ability to write contrapuntal music. To our 20th century ears, it's incredibly difficult to follow all the different parts or voices. It's even harder to play them. J.S. Bach was the undisputed master of the fugue. He was able to improvise many voice fugues using themes provided by others!
As you perform this piece, always make sure you're holding down the bass notes as long as you can, until the next is played. This allows the counterpoint to come alive and creates the Baroque "walking bass line". This is the same concept as a walking bass line in jazz.
Making sure each note (in both the bass and the accompaniment) sustains for as long as possible is called "legato" in classical music. This another part of the "art" of playing classical guitar. If you learn to develop the ability to play with legato now, your left hand classical guitar left hand technique will progress rapidly. Consider this a challenge since I know we're at the beginner level of classical guitar playing.
If you want to hear a Baroque "walking bass line", one famous example is J.S. Bach's "Air on the G String". The cellos play the bass line in "Air on the G String" and the bass line is slow.
Also, one of the concepts discussed in the breakdown of the "Minuet in G Major" by Bach/Petzold is the sequence. A sequence is a repeated rhythmic and intervallic pattern. This piece contains many sequences. I discuss the sequence in measures 5 & 6 but you can also find one in measures 1 & 3. The sequence was a very popular compositional element of Baroque music and one of its most identifiable traits.