Maybe what you describe is what happened to Mars and Martians long time ago...?
Maybe they shot some escape capsules into space, and they landed on another planet to form a new beginning, and it happened to have been the Earth...?
Its said the first Lego brick was not small and colourful, but huge and pitchblack.
We are all Lego Martian stormtrooper figures on some alien child's table.