I am no expert, but I have always joked that instead of the Stone Age, it probably should be called the Wood Age. There were probably some awesome wooden structures or techniques that have been now lost to the ages because they are no longer around.

I'm not sure if it's correct, but I remember a tv show about archeology in East Asia, and they claimed that the problem is that they made too many tools of bamboo (that decompose) instead of tools of stone (that is forever).

Good point, bearing in mind that working wood with only stone and wooden tools is a lot harder than with metals

Working, well, anything we're still going to see traces of would've been even harder harder with only stone and wooden tools than it would be to work wood. It seems pretty reasonable to guess that if we see a culture with stonework and pottery and access to wood, they probably also did stuff with the wood that hasn't survived. (We can then look for evidence, like tools that seems like they they make the most sense to be using for woodwork.)