The 1977 movie -'Close Encounters of the Third Kind' is truly iconic and one of my all time favorites, but there is one thing I am curious about. During the climax we see the aliens returning many people to the earth. Most of them look like they are from a time far behind. Also the other things that the aliens return during the movie are all very old things (taken a long time ago) eg.- Airplanes in mexico, Ship in Mongolia. However there is one exception - the 3 year old kid - Barry, who is taken away by the aliens and returned back soon thereafter (at the end of the movie).
How did this happen? What could be the reason for this exceptional behavior of aliens?