it's more reasonable to assume that the meaning and context of those images was totally different than to project our own onto them. think about how much of our society there is in a teen drawing a dick on a wall. wall-drawing is forbidden. there's even a special word for it that associates it with a countercultural art, if distantly. dicks are obscene and hidden, but nevertheless fascinating. teens are uniquely expected to both obey social rules and submit to the will of others. there's no reason to take any of this as a given for early native american societies.