The modern interest in material origins seems to be just that, modern. Ancients tend to be less interested in this question, and more interested in talking about the order of the world. Many of the ancient Greeks were perfectly fine with the idea that the world always existed, but that it had undergone changes at different times, Greek myths speaking of stages of order and chaos; and many ancient creation myths show these themes: a change of state of the world. There was a primordial world, and then some kind of order. The gods became, and then they either directly or indirectly affect change in the world. And not all stories, even in the same culture, say the same things, but say different things as was needed.
The biblical creation story (the first one) likewise does not present an account of material origins, but instead begins with an already existing world which God crafts and shapes, imbuing the chaotic and primordial world with order and purpose. Right in the beginning we already have the heavens and the earth, and God takes the primordial earth which was "a formless waste" and a primordial oceanic abyss over which the Spirit of God "hovered"; it is out of this primordial world that God shapes and crafts to give it ordered form and purpose. The days of creation acting as poetic structure: dividing light from darkness, dividing the primordial ocean into the waters above and below, and separating the dry earth from the seas; followed then by the creation of creatures to rule--the sun, moon, and stars to rule day and night, things which fly and swim to rule sky and sea, and things which crawl, creep, and walk to rule the dry land.
The YEC view that Genesis 1 presents a material origins account is anachronistic, and forces modern ways of thinking onto an ancient text. The text is not addressing the question of material origins, but rather addressing God's ordered purpose for and in the world, and mankind's place in it--which is to be the image-bearing creature of God. Man's place in creation, unlike other creatures, is as a moral animal to relate with God and reflect God in the ordered creation.
As such it's simply impossible to say that anyone in the ancient world was a "Young Earth Creationist", because that's that is imposing upon ancient people ways of thinking that would have been fundamentally alien to them.
This is why Augustine could look at the creation narrative in Genesis 1 and read it as allegory, and instead looked at the Latin translation of Sirach and say God "created all things in one day". Augustine takes an idea not present in Genesis, creation ex nihilo, to argue that God is the Prime Mover and Cause, and brought forth everything in seminal form. Augustine is also working from, in part, a Neoplatonic philosophical model (see
rationes seminales).
It is these philosophical inquiries that eventually, over centuries, evolve into the basis of western science. As such scientific inquiry as we know it simply does not exist when we are talking about the Old Testament or the Hellenistic mythological corpus. Getting to those bigger questions of "Where did everything come from? And how?" involved centuries of philosophical development in the West. To eventually emerge as a burgeoning new methodology of observation and inquiry which we know today as science. This makes trying to force the Genesis stories into a [pseudo-]scientific model not only impossible, but inappropriate.
-CryptoLutheran