Mmm...fairly speculative but I can accept it as a possibility. =) I guess a talking donkey is less surprising when you've just been speaking direct to God himself a few verses higher. Or maybe he was just too mad to be reasonable, who knows? I'm just glad you didn't say, with arch eyebrows, "Aaaaas an ancient, he was obviously superstitious and didn't know that it donkeys usually can't talk."
Have you ever read another book with talking animals in it that you took to be non-fiction? Something like "Charlotte's Web". Have you read that? When you first realize that the animals are talking, does your mind immediately say.... "fiction" or "non-fiction"?
Forget for a moment that the main topic we are talking about is "the bible. In any other book... what's more likely; someone lied about a talking donkey or it actually happened? Be honest. In any other book you read, a talking donkey would immediately set off that red buzzer in your mind that screams FICTION FICTION FICTION. Once you realize that, ask yourself why you give the bible a free pass and no other books? Couldn't it simply be that you have been indoctrinated by people close to you to believe that the bible deserves a free pass when it comes to things that don't stack well with reality? And that those people were also indoctrinated by others who were themselves indoctrinated... etc, etc, all the way back?
If that is the case, can you really say you are looking for truth if you treat that book entirely differently from other books? The very minute you stop using the same examination and reasoning techniques that you would use for every other book, is the same minute you have stopped looking for the truth.
It's not that talking Donkeys would be impossible if God were real. Of course they could exist. Anything could exist then. Talking ants could be possible. Talking trees could be possible. It's also possible if Allah were real that Mohammed flew up to heaven on a winged horse. It's also possible that Xenu is part of an intergalactic empire. The question you have to ask is... given the amount of evidence we have that animals can talk (zero), or that horses can fly (zero) is it more likely that someone made it up, or that it actually happened? We know people lie. It happens all the time.
In that light, do you REALLY see your stance as the most logical? I would have to say that NOT believing in talking donkeys is far more logical and reasonable.
There's a lot of questions in there. Don't answer all of them. Just think about them, get the gist of what I'm saying, then tell me what you think.