What if the ancient structures in Europe, for instance the megalithic tombs, the dolmens and henge monuments are reconstructions of older monuments?

We would never be able to fully uncover the older dates with our current dating methods, but I personally find it extremely unlikely that we have a 7000 year gap in construction between the Tas Tepeler sites in Turkey and the oldest stone structure in Northern Europe at the Carrowmore cemetery.

It is possible that we had burial mounds, or passage tombs, dolmens or henge monuments created from wood, that kept being rebuild for a very long time, possibly thousands of years, that eventually got reconstructed by stone, either a very long time ago, or not as great as they may have not been very skilled working with stone yet, who knows..

Eventually about 5600 years ago the Neolithic builder culture started to develop and they could have possibly discovered the ruins of these ancient structures and eventually these stone structures were reconstructed by them.