The context, for one.You're right, they probably didn't. If you see it as poetic language and not literal, I guess there's nothing for me to argue with you about. The question is, how do you decide what's literal and what's metaphorical in the Bible?
For example, Earth in Scripture can actually mean society. Read Genesis 11:1, you'll see it. (No planet has a language.)
So, that's what Peter meant when he wrote about the Earth in 2 Peter 3. "The heavens and the Earth that now are." No different planet after the Flood...different society of people, though.
And heavens can mean, governments and authorities...see Ephesians 3:10.
If just any Joe Blo could accurately grasp the meaning behind the Scriptures....why did Jesus make the statement @ Luke 10:21, that to some, it would be hidden? And Daniel 12 says the 'words would be secret'. Until the time of the end (Last Days). You know, Isaiah 2:1-4 ties in with this, happening as it does in the Last Days.
Have a good night.