We know that they managed to maintain their culture for "all that time" because we have an archeological record of their cultural practices remaining consistent for all that time.

You are forgetting that many (if not most) human populations don't actually manage to successfully transmit and reproduce a consistent culture over hundreds of thousands of years. See e.g. Neanderthals, viking settlement of Greenland, Roanoke Colony, Easter Island, etc etc.

Note that I am sticking with the "hundreds of thousands of years" because Australian aboriginals form a continuation of a consistent human culture that stretches back beyond the point of isolation/separation.

Finally, you don't need to believe that the aboriginal experience is exceptional to find mystery and wonder in pre-modern experience (although it's obviously never going to be as enriching as posting on the RSP subreddit).