Yes, I agree it is metaphorical. If you agree as well, then the original author(s) did not actually believe the world was a literal flat earth with a solid dome for the heavens.
The Bible describes a flat Earth because to the men who wrote it, it looked flat with a dome of sky. If it were written by God, the ‘creator of the universe,’ it would have been described accurately as well as poetically.
Yes, they wrote from the perspective of what they observed. However, there are aspects of the creation account that they could not have observed. In particular, writing that God created the entire universe. This has been a long standing debate with those who hold an eternal universe and dates back to Aristotle.
The ancient Greek philosopher Aristotle argued that the world must have existed from eternity in his Physics as follows. In Book I, he argues that everything that comes into existence does so from a substratum. Therefore, if the underlying matter of the universe came into existence, it would come into existence from a substratum. But the nature of matter is precisely to be the substratum from which other things arise. Consequently, the underlying matter of the universe could have come into existence only from an already existing matter exactly like itself; to assume that the underlying matter of the universe came into existence would require assuming that an underlying matter already existed. As this assumption is self-contradictory, Aristotle argued, matter must be eternal.
In was only in the past century or so that scientists started to believe in a finite age of the universe. Prior, they had all held to some model of an eternal universe.
However, most scientists throughout the 19th century and into the first decades of the 20th century presumed that the universe itself was Steady State and eternal, possibly with stars coming and going but no changes occurring at the largest scale known at the time.
This poses a problem now for modern scientists of what caused the initial state of the universe. And the Bible gives the answer for this, which has been consistent with what it has been saying all along.