The tombs of the people who worked on the Great Pyramids actually prove that they were not slaves. These tombs were more than 4,000 years old and discovered in the 1990's by a tourist. They are 9 feet deep shafts and held perfectly persevered skeletons of the pyramid builders. Archaeologists believe that not slaves, but paid workers built the Egyptian pyramids.
Many archaeologists have concluded that the Great Pyramids were built by slaves. The amount of labor it would have taken to build such large structures would have depended largely on slave labor. Also, slave labor was very common during ancient times. The discovery that some pyramid workers were buried in tombs does not mean that these workers were not slaves.
How does a tomb prove that a person was not a slave? Just because the people were entombed does not mean that they were not slaves. They could have been highly respected and still have been slaves. The tombs merely show that these people existed and were laid to rest there, nothing more.
People want to think that the people who made the Great Pyramid are not slaves, but there's no reason the discovery of some tombs necessarily leads to that conclusion. Too much is still unknown about the ancient Egyptians to make such a proclamation. The majority of available evidence still points to the likelihood that the builders were slaves.