There are four Egyptian creation myths, all similar.
The different creation myths have some elements in common. They all held that the world had arisen out of the lifeless waters of chaos, called Nu. They also included a pyramid-shaped mound, called the benben, which was the first thing to emerge from the waters. These elements were likely inspired by the flooding of the Nile River each year; the receding floodwaters left fertile soil in their wake, and the Egyptians may have equated this with the emergence of life from the primeval chaos. The imagery of the pyramidal mound derived from the highest mounds of earth emerging as the river receded.
Wikipedia
Sunrise at Creation: The sun rises over the circular mound of creation as goddesses pour out the primeval waters around it
Scanned from the book Ancient Egypt, edited by David P. Silverman, p. 121; photograph from the Book of the Dead of Khensumose
Thales of Miletus, considered the first Greek philosophical sage (Melitus is in modern-day Turkey) was wealthy and may have traveled to Egypt and saw these creation myths on the walls of temples (where we found them also).
Thales (around 600 B.C.) brought them home and created a philosophy around them: everything on the Earth started as water. It's an astounding thing to say, because we don't observe this behavior in nature. You can find hints of it, when, say, you evaporate a glass of seawater to dryness, but nice pure rain water doesn't do this. But his theory of elements starts with water, from which all other matter is formed. The land, the sky, eventually fire.
Aristotle laid out his own thinking about matter and form which may shed some light on the ideas of Thales, in Metaphysics 983 b6 8–11, 17–21. (The passage contains words that were later adopted by science with quite different meanings.)
That from which is everything that exists and from which it first becomes and into which it is rendered at last, its substance remaining under it, but transforming in qualities, that they say is the element and principle of things that are. …For it is necessary that there be some nature (φύσις), either one or more than one, from which become the other things of the object being saved... Thales the founder of this type of philosophy says that it is water.
Wikipedia: Thales of Miletus
This marks the beginning of the Greek Philosopher, more interested in the thinking than in making their philosophy describe their observations. It's a trend that will last at least past 300 B.C. Thales worked in astronomy, hydraulics, geometry and the nature of God, but his ideas about water had the most influence.
The Miletus School of philosophers followed and expounded on what Thales taught. Water became a first "element" or "Principle" of matter.
Anaximander thought there were four elements, each primordial. They are recylced as the "waste" of mortality.
"Anaximander taught, then, that there was an eternal. The indestructible something out of which everything arises, and into which everything returns; a boundless stock from which the waste of existence is continually made good, “elements.”. That is only the natural development of the thought we have ascribed to Thales, and there can be no doubt that Anaximander at least formulated it distinctly. Indeed, we can still follow to some extent the reasoning which led him to do so. Thales had regarded water as the most likely thing to be that of which all others are forms; Anaximander appears to have asked how the primary substance could be one of these particular things. His argument seems to be preserved by Aristotle, who has the following passage in his discussion of the Infinite: "Further, there cannot be a single, simple body which is infinite, either, as some hold, one distinct from the elements, which they then derive from it, or without this qualification. For there are some who make this. (i.e. a body distinct from the elements). the infinite, and not air or water, in order that the other things may not be destroyed by their infinity. They are in opposition one to another. air is cold, water moist, and fire hot. and therefore, if any one of them were infinite, the rest would have ceased to be by this time. Accordingly they say that what is infinite is something other than the elements, and from it the elements arise.'—Aristotle Physics. F, 5 204 b 22 (Ritter and Preller (1898) Historia Philosophiae Graecae, section 16 b)."
Anaximenes settled back on air as the primordial element. “Just as our soul...being air holds us together, so pneuma and air encompass [and guard] the whole world.” (Vamvacas, Constantine J. (2009), "Anaximenes of Miletus (ca. 585–525 B.C.)", The Founders of Western Thought – the Presocratics, Springer Netherlands, pp. 45–51). The phrase "breath of life" comes from Anaximenes.
Minor Miletians selected earth or fire as the primordial element.
Empedocles later selected all four.
Empedocles established four ultimate elements which make all the structures in the world—fire, air, water, earth.[29][40] Empedocles called these four elements "roots", which he also identified with the mythical names of Zeus, Hera, Nestis, and Aidoneus[41] (e.g., "Now hear the fourfold roots of everything: enlivening Hera, Hades, shining Zeus. And Nestis, moistening mortal springs with tears").[42] Empedocles never used the term "element" (στοιχεῖον, stoicheion), which seems to have been first used by Plato.[43] According to the different proportions in which these four indestructible and unchangeable elements are combined with each other the difference of the structure is produced.[29] It is in the aggregation and segregation of elements thus arising, that Empedocles, like the atomists, found the real process which corresponds to what is popularly termed growth, increase or decrease. Nothing new comes or can come into being; the only change that can occur is a change in the juxtaposition of element with element.[29] This theory of the four elements became the standard dogma for the next two thousand years.
Wikipedia: Empedocles
And thus was the stage set for the disaster of alchemy. But the ideas needed hero, a believable hero. A hero of ideas so believed that no one would consider calling them wrong. These ideas needed Plato.