I know you have a great take on all this, but they did make it pretty clear and that is why the OT has been translated that way.
It also matches much of other text where they state and mean a single day, not other imagined lengths of time.
Most of the time creationist trying to rationalize the mythology use this excuse, but they ignore other verses that help place it into context.
I do not endorse this site in any way, but it makes good sense for this exercise.
A Day Is A Day
If a day means more than 24-hour period, then how are we to interpret the following verses, as well as scores of others. “Six days shalt thou labor, and do all thy work: But the seventh day is the Sabbath. . . . in it thou shalt not work... For in six days the Lord made heaven and earth… and rested the seventh day” (Exodus 20:9-11).
Genesis 1:16 (“And God made two great lights: The greater light to rule the day and the lesser light to rule the night”
states the sun rules the day and the moon rules the night. This obviously is referring to time as we know it, time with days that are 24 hours long with daylight ruling half of each.
If a day is an era, then much of the Old Testament becomes chaotic. For example, in each of the following verses the same Hebrew word “yom” is employed: “And the flood was forty days upon the earth” (Genesis 7: 1 7), “And he [Moses] was there with the Lord forty days and forty nights” (Exodus 34:28), and “Thus I fell down before the Lord forty days and forty nights...” (Deuteronomy 9:25). If “yom” means era instead of a 24-hour period, Moses was “there with the Lord” for a VERY long time.
Adam was made on the sixth day (Genesis 1:26-31) which was supposedly thousand of years long. This was followed by the 7th day which was also thousands of years long. Following the 7th day, Adam fell into sin and was expelled from the Garden. This would mean Adam lived thousands of years, which is false, since he died at age 930 (Genesis 5:5).
enesis 1:5 surely spoke of literal day and literal night, and the inference from the statement, “And the evening and the morning were the first day,” is that it was a literal day of evening and morning, 24-hours. There is no Biblical evidence that the days of this chapter were longer periods.