Lovely sketches!
3 and 5 really evoke a sense of the aquatic and have more of the Pre-Columbian aesthetic. I'm not sure how you plan to use the faces in your final, but if they are embedded into the rock of a cliff/mountain side I think the structural integration of 4 works rather nicely.
As for the pillars, you immediately recognize 4,11, 12 as being aquatic, but there is something about the shape and totem inspiration of 1 that I find really interesting.
Very cool project, and I look forward to seeing the finished piece!