They mighta not been the friendliest bunch, but I bet yer "friends" on YouTube pretty much had it right...
Gawd I lothe YouTube lol
Anyhoo - yeah, with the spark plug in there's so much compression in the engine you'll not be able to turn the wheel just by pushing the bike - if you could it'd be a very bad thing as it'd be truly broken lol. I weigh about 190lbs and even with my full body weight on the bike, pedaling madly - my back wheel will often skid, sometimes up to a coupla feet before the engine starts to turn over.
Engine compression is a wonderful thing
Put it all back together, if yer missing just one clutch cover
screw you'll be fine (get another one from a hardware store when you can), give it some fuel mixed no more than 24/1 with a good 2stroke oil, pull in that clutch, pedal like a madman, snap the clutch out - but keep pedaling
It'll fire up sooner or later, they're a bit stubborn when new - just keep at it