What is with all this other stuff? Calculations? Days for years added to some obscure events?
I obviously believe that all of that stuff is manmade if for no other reason than to make the inventor and/or the followers feel special. (as rebel8 pointed out) I believe that real truth that is closest to anything that would come from G-d would be so simple and yet so profound that many would not choose to believe it simply because truth just cannot be that simple. Especially to the individuals who love riddles.