Maybe John traveled through the past. Perhaps Sebeacans are OUR space-faring ancestors and Humans are a long lost Sebeacan group of settlers who adapted to Earth's enviorment. I think revealing that the peacekeepers are actually ascendents or descendants of humans would be taking things a bit far. Star Trek has beaten this thing into the ground and has suffered in quality because of it. For once I want to see a Sci Fi show that remains humble, some things in life just are they don't need a divine connection.
Wormholes are versetile.
They can travel to another area of space and time. Its possible that John traveled thoasands of years into the future and infact, Sebeacans are Human ancestors. Perhaps the long forgotten Sebeacan homeworld is Earth. Maybe John didn't travel as far into the Universe as once suspected. Maybe John traveled through the past.