Working with shapes to play bass lines is how many bass player get started playing lines with chord changes. I guess you might say or at least in my opinion you never really stop using these shapes when you are playing. You might not be conscious of the shapes but you still use them and new ideas you might grab the shape in your mind to quickly absorb it.
So now that you have a shape of an arpeggio you will use to add lines to the chords in a song. It is time to explore ways to use this shape to produce creative bass lines with interesting rhythms. This where the theory comes in. This first video of the series id=s about root and fifth. This would be the most simple shape as well as the one that can be used in the most places.