Very interesting.
Thanks — the cave texts are standalone symbols, and the fact that they’re a match for later writing systems suggests some kind of long-term development. Unless a long, long text is found, there’s no way to figure it out, and even with that, given the extreme antiquity, probably not even then. It looks like a primer of some sort — here’s the symbol for “bull” or the first letter of “bull”, and here’s the picture of the bull itself...