I voted "allegorical" although the correct term would be "mythical". The whole story of the captivity and exodus is untraceable not only in Egyptian records but also in the archeology of the region, so it's not history. A myth is a story told to make a point — like the parables told by Jesus. Two historical facts — the Egyptian rule over Canaan in the Bronze Age and the expulsion of the Hyksos from Egypt, provided the basic framework, but the point of the story is to define the Israelites as a people and to define their relationship with their tribal god, Yahweh.
This ties in nicely as a framework with
@Jayhawker Soule post before yours. I particularly appreciate his capitalization of the word myth to mean something greater than just a type of story. It would be Story with a capital S, versus a story. It is the nature of the narrative of a people that each can identify themselves with. It's a living breathing organic thing.
It's the same thing really on our own personal level with the narratives we tell ourselves about ourselves. We are editors of the narrative of history in our self-reflections. "Who am I," gets identified with that story arc we have created. The actuality of those things happening exactly as we've told ourselves is point of great fallacy in believing that everything we remember was literally true. Memory is simply not that accurate at all. So we "believe" that "history" of our lives and the many meanings and values we identify with those memories. It is the personal myth that we all have.
And so I see the cultural myth to be the individual's myths adding to the collective Myth. And then our personal myth and culture myth become our collective Myth. It is how we see ourselves in the world, what is our tribe, who is "our people"? This was an early advance in civilization moving away from bloodlines and kinship systems, to an ethno-identification. It is a fiction loosely created around bloodlines and shared Narrative. This evolved later on into the fiction of Nation States, and so forth.
Each and everyone one of them is fused together by their Mythologies. It's what binds us together in our conscious minds. "Who are my people? Who am I?"
Personally, I find this, like many OT myths, deeply disturbing. We are told that Yahweh "hardened the pharaoh's heart" — so, if he could do that, why didn't he do the opposite and encourage the pharaoh to let them go? Because he wanted to demonstrate his power by sending plagues. As a myth, this may only tell us what the israelites believed about their god, rather than the truth, but if it's inaccurate, why didn't he correct them? It's like Job, where Yahweh tortures a man to win a bet. Either this is a very unpleasant god, or one so weak that he can't correct misconceptions about himself.
This dilemma you present here begins with a presupposition that the image of God you see on the pages of scripture, actually, literally, scientifically even, somehow are not themselves metaphors. That assumes the literalist view of these things as factual descriptions, rather than symbolic and representative of an aspect of man's ideas of God on its pages. The mistake comes when one assumes if it is not literally true, or if you see some contradiction of logic, that means there is nothing worthy to see there, or worse that's it's 'just a lie'.
I personally think that can be an easy failing of those exiting from literalist religious experience. It is still seeing in somewhat binary terms. In mythic-literal modes of faith, the truth or meaning of the story is fused with facts of the story. But in exiting that stage of faith there is a transition away from that mode of finding truth and meaning, into a rational, fact-based mode finding truth and meaning.
Contradictions in the story, can be understood to mean that the story is not factual, and therefore the meaning of the story is at risk. The baby and the bathwater are one and the same, and either stand or fall to the mythic-literal mind, as well at the emerging rational mind. It is still learning how to master being able to find the meaning of the story, without the details of the story needing to factual or withstand critical analysis.
Eventually, meaning becomes more abstracted, rather than fused to the facts. We create meaning, and always have. And these are our Stories about the great Mystery of our being. It is meaning projected on Myth, to tell us who we are.