nice analysis @Air
But I would suggest most newbie to ask for some1 experience, everybody will have their own type of starting hero to teach newbie, for me example will be zeus, while my fren is teaching newbie using sniper. I remember i was first forced to play CM (I would not argue cos she so damn cute in dota 1 *ahem*)
Let those who are experience found out ur type, then u develop through there and bring ur potential, master a type 1st, then try other hero to learn them, then back to ur best role.
Mostly people start support cos they was forced to when play with friend, dota is not meant to start solo, there must be some1 who drag you in the dota world. And most importantly, support is not easy for starter, cos it is very frustrating when u get all the flame especially when u dono what u shud do and buy.
I would suggest some starter hero, which is zeus, sniper, bone clintz, cm, drow, warlock. Nuker and range is always best for starter to learn, teach them to survive, to run when ganked (e.g buying shadow blade). Also make sure experience player coach him enuf to win at least Hard AI before real match, cr8 new account to join them, or watch their game and give suggest.
i rather ask people use tide or VS instead of CM for newbie hehe. CM is very weak. CM user need proper way to dodge some skill especially arrow or hook for that or else normally feed only when facing pudge.