Kind of as other said, it was buried. From what I have read archaeological finds are about piecing together good guesses. Sure some wood is rot resistant but I suspect you would be hard pressed to find wood sitting outside for 1000+ years on the ground that early civilization would find appeasing to build with. Anything is possible but I am guessing it either fell natural or was harvested by those people and they decided to build with it somewhere plus or minus a thousand years.

It was probably buried under anoxic conditions, which would weaken it and make it less suitable for new construction.

"Intact enough to be recognized" is a lower standard than "intact enough to be useful as a building material".