My first impression of this thing was like a ship's mast, with rungs for climbing. Maybe because that is something I imagined someone holding on to in a body of water.
I agree that they might also be interpreted as standing behind the log, in which case the log would be stationary. The reason why I interpreted them as part of the log was probably that they don't go nearly as deep as the guy's feet, and the part above the log is made even longer than the part below. If the thought were "anchored in the ground", then maybe the part below would be extended longer.
The log itself is pretty rudimentary, it's basically a long cylinder with a streak of paint. Indeed the thickness varies, but I'm not sure whether this is intentional. The artist has difficulties drawing shapes that pass behind other shapes. And the pose seems to have given him severe difficulties. One arm is much longer than the other.
It's also difficult that this is with the "pooling" green paint which has the tendency to be darker at the edges, creating the illusion of lines. It is not always clear when we are looking at a pen line or a paint edge. These are the pen lines I think I see with some certainty:
Edit: by the way, when drawing this I noticed the line of the body passes through the line of the front arm. This could mean that the arm was drawn after the body and not planned very well.