Chinamitl is used in K'ek'chi' and K'iche' documents and has to do with Chibal or Chi'ibal, which are patrilineal groups. I suppose then that in the case of the K'ek'chi' and K'iche' that they are using the word Chinamitl figuratively or metaphorically. Most Mesoamerican peoples believed that people were made of corn, the association with the Chinamitl or the reed mat used as the base for floating gardens or chinampas would make sense. Reed mats were also used to support rulers and therefore would have that same sort of correlation. I may be way off base here... food for thought.