The idea of a paradise came from the Egyptians, they thought after they died and went threw the underworld going through some triles and tribulations that after thier last test having thier heart weighed if they past the test they would live forever. This place was called the field of reeds. If they did not past the test and thier heart was unpure they would be eaten by a beast and die a second death forever gone.
I can see the Watchtower taking this factoid and twisting it to "prove" that it was well known among the nations that a Paradise Earth was God's original purpose for mankind.