Scott J,
How did the ancients read Genesis 1?
YEC think they read it by understanding that God created the universe in six literal 24 hour days beginning with:
A formless earth in empty space.
The creation of light for this earth without first creating the sun, moon, and stars.
The creation of the sky.
The creation of land and seas.
And then, finally, the creation of the sun in which the earth finally starts to revolve.
I would like to suggest that the YEC interpretation is probably not the interpretation of the ancients, but I, like you, have no way of proving that.
However, the OT and NT repeatedly speaks of God stretching out the heavens and laying the foundation of the earth, something that comports very nicely with Genesis 1:1 being understood to be the creation of the universe in toto, including the sun, moon, stars, galaxies, solar sytems, planets, etc. The age of this fully functioning universe is not defined in Scripture. The foundation of the earth is described, however, in verse two of Genesis 1. The Holy Spirit hovered over the face of the earth, but we don't know for how long.
Then God said let there be light and the clouds around the earth thinned and the light from the previously created sun filtered through to the earth's surface.
On day four, God didn't create the sun, he appointed the sun and moon, and stars, to be lights for the seasons, and to govern the day and the night. This is a perfectly normal understanding of "asa" in the Hebrew.
So perhaps, our little Hebrew boys and girls understood Genesis 1 in a completely different way than YEC. And their understanding would have been literal and consistant with inerrancy.