Concept art, interviews and manuals aside, Sonic 1 - 3nK has no humans in it aside from Robotnik.
Crackdude, you parsed my message incorrectly. Obviously, Robotnik is taking over the world, but, the result of his efforts in the first 3 games is environmental disaster. Chemical Plants, Oil Oceans, Flying Batteries firebombing. THAT aspect is missing from SA1+. From SA1 onward Robotnik is taking over an already developed world.
You guys seriously can't see the Nature vs Man aspect of first 3 games?