A Swami from Sivananda ashram gave me his opinion that Babaji was an archetype.
Who is Babaji? Some specific personage somewhere? Some body sitting in lotus position? Babaji is your own Self. Babaji is everybody. His name is perfect. Babaji is a very common title in India, like Maharajji. "Ji" is appended to a name to denote respect. Baba is so common that one would be hard pressed not to run into a baba at some point.
"The guru is not external."
Brock, true enough that the honorific title in India is widespread, but when speaking of Babaji we usually refer to Mahavatar Babaji the guru of Lahiri Mahasaya, a reincarnated soul, an avatar, not an archetype in the general sense