They were never intended to be allegory. They were always seriously believed. It was only later that some liberal religious figures considered them to be allegory.

@Krish55
Conscious intent is not particularly relevant. Storytelling has a biological basis, and an evolutionary function. What humans intend makes little difference. The symbolic values are present in the stories regardless of what the teller perceives, or the story would be forgotten. When stories are preserved and passed to subsequent generations, it is because they have proven adaptive - just as any biological trait.

@skado True, but that doesn't support your original claim about these stories being allegory. They contain allegory and that's the best way to understand them. But that doesn't mean that they are allegory. Intent is relevant to that latter determination.

I may use a BMW as a tractor, but that doesn't mean that it is a tractor...

Agnosticism is the default condition; a newborn has no knowledge of either an Abrahamic god or fairy tales.

Because I say so, which is as valid as anything else I've read here.