Do you think Revelation should be read literally?
The early church understood Revelation to be metaphoric, and some had to be explained the meanings.
But the Jews, in ancient days, who Genesis was initially written to, never thought of creation in metaphoric terms, because it wasn't written in that style.
I don't read Hebrew, but at times I have translated words and phrases, backed by experts in the language. The one thing I understand about Hebrew vs English is that the language has more meaning to its words than often English does. More can be involved with words than what "we" non Hebrew speakers understand.
Such as John 8:58 Jesus said unto them, Verily, verily, I say unto you, Before Abraham was, I am.
We read I am as, Iam this or I am that. But Christ was using I AM, a name that God uses for himself. In essence claiming to be God himself. Which then was followed by John 8:59 Then took they up stones to cast at him: but Jesus hid himself, and went out of the temple, [[going through the midst of them, and so passed by.]]
If I am were simply as we read it, it never would have stirred the pharisees to want to kill him.
I do believe the timeline in Genesis is literal. BUT, I understand the whole 1 day is as a thousand years thinking. And though I don't choose to believe it, I think it can be a possibility. Its just not really important when it comes to salvation.
If I heard of a credible source, who was a Hebrew expert, who could explain Genesis being written metaphorically, I might be more accepting of this theory.
But so far as I know, the only arguments I've heard for a day being longer than a day, are people who don't understand fluently Hebrew.
Once again, as far as I know.