So, you are right to say that we don't know if it is Noah's Ark, but you are also right (in my opinion) to present the evidence as you found it, and say, "if it is not Noah's Ark, what is it? And how can we explain all the evidence suggesting that it is Noah's Ark, if it isn't?"
And, I think your point about "probability" rather than "proof," is a strong one. I'd keep hammering at that. "Maybe it isn't, but what if it is? How would that change your relationship with God?" Read More...