Well, given that all great apes build loose "nests" with leaves and branches to sleep in the answer is probably something like that, but we have no proof it.

The oldest evidence of structures built by hominids are simple huts with a roof of branches and a base line of stones like the ones of Terra Amata, France and Chichibu, Japan. Dating is uneasy but they might be as old as 400,000 or 500,000 years old. In consequence, they are far older than the origin of our own species and were built by individuals of the Homo erectus species complex.

I think that you can make your questions a little more clear? There are caves that show structured areas. Some even have been used and reused over and over again (I believe by different species of humans) throughout time. That said, Are you interested in Modern Humans? If so are you asking about post cave dwellings with actual huts or floors?

hi! while there are some archaeologists here, it might be worth cross-posting this to /r/AskAnthropology. Meanwhile, there have been related questions in this sub, so check these out for previous responses

What is the oldest known human structure?

possibly of interest:

What is the oldest human structure that has been in continuous use?

Which building is the oldest in the world, but not a ruin and is still used?

What's the oldest building in the world that has been in continual use/occupation?

What kinds of ancient structures are still in use today?

Building on the oldest continually used building question, what is the oldest continually inhabited city on earth?