"It can be 24 hours within the story. "
I agree. I just don't think the text lends itself to this (my opinion).
"They didn't understand because they thought it to be literal. "
So you were alive then and talked to them about it? Again, this is your assumption.
"How would you have understood it without the guidance from Jesus, if you were a jew at the time of Christ and that you had read it literally?"
I wouldn't have understood a lot of the OT without the guidence of Christ, Paul and many others. Does that make it any less literal in 2nd kings? Nope.
Lets examine this passage... first verse
"And it came to pass, when the LORD would take up Elijah into heaven by a whirlwind, that Elijah went with Elisha from Gilgal. "
If this passage is nonliteral Eijah must have not literally gone to Gilgal, but he literally did.
" And fifty men of the sons of the prophets went, and stood to view afar off: and they two stood by Jordan.
2Ki 2:8 And Elijah took his mantle, and wrapped [it] together, and smote the waters, and they were divided hither and thither, so that they two went over on dry ground.
2Ki 2:9 And it came to pass, when they were gone over, that Elijah said unto Elisha, Ask what I shall do for thee, before I be taken away from thee. And Elisha said, I pray thee, let a double portion of thy spirit be upon me.
2Ki 2:10 And he said, Thou hast asked a hard thing: [nevertheless], if thou see me [when I am] taken from thee, it shall be so unto thee; but if not, it shall not be [so].
2Ki 2:11 And it came to pass, as they still went on, and talked, that, behold, [there appeared] a chariot of fire, and horses of fire, and parted them both asunder; and Elijah went up by a whirlwind into heaven.
"
Here also, the jordan must be a nonliteral place for this passage to be nonliteral..but there is a real river named Jordan.
there are tons of hints that tell us this passage is quite literal.