I am far from an expert on this topic, but I am a keen observer of what I call 'spiritual' art - art created as some form of religious or spiritual significance.
From what I understand, much of the traditional aboriginal 'art' - including spiritual art - was based on the spoken word and story cycles. These became elaborate 'plays' or ceremonies which were handed down, complete with costumes, musical (special effect) intruments, etc.
In less than 50 years of the notion of the written word, the visual arts, and good intentions (modernisation) - a good many of the spoken arts have been lost forever. I could easily play with the notion that much of what we consider aboriginal art - such as cave paintings, rock carvings, etc - could have been merely part of the set scenery, like we would see in a theatre. The real show was out in front - like I say, we will never know - unless someone masters time travel.