Do you think we will ever know for sure how the pyramids and stonehenge and other structures were built without any heavy-lifting equipment?

Answer 1

The simple answer is no. Why? What was once on top has been slowly, over years-centuries, pushed many feet down. This is known as the Law of Superposition, that is what is many feet under the surface is older than what is on top. This theory is also known as stratification. Hence, the archaeologist has one method of dating by seriated chronology.

The heavy equipment as you put it is necessary to move the earth. This along with satellite pictures, geology reports, GPS, x-ray equipment, old maps, mythology-stories about some event, and local history all provide the archaeologist with clues where to find the artifacts.