I understand the point that we might be too backwards to see the signs of hyper-advanced civilisations, but how is it that _all_ the other civilizations are su

I understand the point that we might be too backwards to see the signs of hyper-advanced civilisations, but how is it that _all_ the other civilizations are super advanced to the point that any trace they leave is impossible to understand? And, won't uncontacted tribes in the amazon have seen airplanes and such?