Your question seems to have been about what was once called, 'the missing link'. In those days it was assumed that we were descended from the apes and that there must be a species in between monkeys and humans. But all that has changed after the discovery of various forms of hominid fossils of various periods.
Today we know that the early hominids and the apes branched off from a common ancestral line some 6 million years back. Since then we have found hominids of varying degrees of evolutionary traits all across the range of millennia.
In this way we might say nothing much is left. But at the same time any more info is welcome also.
There are still countless holes in our knowledge with regard to how we evolved from apes to homo sapiens. Language and culture just being two. The fossil records are not complete and finding more sites where we lived and evolved could answer some of the cultural questions but as you know, how languages and the written word developed over time may never be known.....