What do you mean by "there's a possibility"? Do you mean, "it's possible the people who made the game wanted us to understand that Tifa is such an entity, and therefore left some very subtle hints?"
Yes I think they left hints but perhaps more to play with the insight of the players than to allow them to discover the truth. I say "there's a possibility" to convey the idea that I'm not sure there isn't. In any case for me this potential discovery would not be the ultimate revelation but an important piece of evidence necessary to solve the investigation.
It was said that the initial concept of this game was to revolve around the investigation of a detective in New York and that the concept was recycled for the development of
Parasite Eve. However, I strongly feel the atmosphere of a
film noir movie when I walk through the streets of Midgar (sector 8). I think that maybe some other elements of the basic concept remained like the possibility to investigate and discover something
interesting/subversive.
I have already expressed on this forum my intuition that the Planet (Lifestream) is responsible for the tragic events we are witnessing.
Or do you mean, "Canon hasn't categorically and specifically stated she isn't such an entity, so it's possible she is?"
According to my hypothesis, the Canon would be to the player the equivalent of the shadow theater that animates the wall in the
Allegory of the cave (Plato).
Rather as in the Bible no one specifically states that Jesus is NOT a racoon, so it's possible he might be.
If someone suspects Jesus of being a racoon I might advise him to go investigate in Racoon City
(Please take this last proposition as a simple humor)