Creating a path from the center points of a selection?

[denzjos]

I tried this: 
- select the black line with the Fuzzy Selection Tool
gimp menu :
- Select / To Path
- Select / None
- on path, right click : 
  - Tools / Cropping and Slicing / Crop path by rectangle
  - Edit / Break path apart
  - Tools / Generate intermediate paths  (3)
done (maybe ofnuts can suggest a shorter way to do this)