Who actually WAS the Earthling?

I'm thinking it was Shawn (Ricky Schroder) rather than Patrick Foley (William Holden). The -ing suffix indicates a youngster. But can anyone provide rationale for the title? I am assuming it was so-titled because we're all creatures on the earth, struggling to survive. Much like other mammals.

Even though people can live primitively, no other of God's creatures can love like us humans do. That was one theme the movie touched on, hence it's title. Your thoughts?