Design goal: Produce a tall structure, visible for many miles, capable of withstanding floods, storms, earthquakes, using lifting equipment made out of wood (metal is far too scarce and, thus, expensive).
From a position of total ignorance, illiteracy and inability to travel to other parts of the planet (in the bronze/iron age), using only your intuition what would be a good shape? Tall and thin might fall over in a quake. Vertical sides would demand a lot of building material if it was layers and solid at the core. A hollow box would force a vaulted wooden roof, which would not last forever, tge way stone does. Also storm winds pose a challenge for vertical faces.
Pyramid is about the only logical shape left, after eliminating all the shapes which would likely fail.
Convergent design solutions in Egypt, Mexico, Vietnam, Solsbury Hill and wherever else.
IMHO, of course.