I certainly think that humans are not the limit of evolutionary complexity. There may indeed be post–human entities, either organic or silicon–based, which can in some respects surpass what a human can do. I think it would be rather surprising if our mental capacities were matched to understanding all the keys levels of reality. The chimpanzees certainly aren't, so why should ours be either? So there may be levels that will have to await some post-human emergence.