Does not surprise me. Here is what troubles me. Modern man punctuated into existence 70,000 to 240,000 ears ago depending upon whom you believe. 5000 years ago Man was still a stone age technologist. In that short amount of time he landed on the Moon. Yet, it took him 35 to 120 times longer to go from making spearheads to stone buildings without adding anything new to his anatomy.
This would only make sense if world human population remained too low for society to support clever inventive types. I think there is a lot of interesting stuff buried deeper than archeologists tend to dig that will eventually crop up and push advanced technology further back in time.
That scenario doesn’t seem too likely, even if the lower figure of 70K (or as some would have it 40K) is accepted.
The problem is perhaps analogous to the search for exoplanets — when the first one was verified back in the 1990s, the technology was such that only very large bodies could be detected. Now nearly twenty years on bodies only 2 or 3 times Earth’s size can be detected.
With perishable materials, much less will survive over these huge intervals; woven material was used a very long time ago, but has only survived in the form of the imprints left on, say, clay. But the stone tools, arrowheads, etc, will be there for millions of years.
The oldest multirow (cultivated) barley sample AFAIK goes back to RC 14000 years ago, dug up in the Near East somewhere. It’s amazing that it survived, but it pushes back the verified age of agriculture. Postholes from structures rather like longhouses have been dated to 800K, and while it’s possible that a hunter-gatherer culture may have built shelters, the very nature of a moving food supply makes it unlikely that some form of agriculture was NOT being practiced there.
For much of the last 2 million years the oceans have been reduced in depth by glaciers on the highlands of the continents, and it’s perfectly likely that most of what we’d consider human prehistory left its traces on what is now the continental shelf.