Of course you’re right to be sceptical,
I'm not sceptical at all.
I have an intense interest in the world of Sumer.
I agree that the ancient myths, texts, star lore etc has more than one application.
But the invisible precedes the visible, and it's nigh impossible to convey meaning of the invisible. That is why the inner workings of humans which lead to ascension were discussed in outward terms. Hence, an analogous story, a star myth, a totem, iconography etc.
I am most interested in your work. That is why I responded to this thread.
For me, transcendence of the physical was the goal of Sumerians, the Golden Agers, later the Egyptians, the Yogis and so on. However, as the journey up the Tree is a personal one-off experience, all reference to it can only be in rather general terms.
The object of all this was to start aspirants on the path and guide them as best as possible. We can see this in the icons depicting the winged birdman holding the pine cone pointed at the pineal gland. Then, we get the later Hermetic texts and alchemy which to some is merely the transmutation of a base metal into gold, not understanding its true application.
Who was the First? That could be a worthwhile goal of your research.