A second answer:

The benefit of using a figurative rather than a literal expression may lie in its being easier to pronounce; its suitability for the rhythm of speech, in verse or prose; rhetorical correspondence, wordplay, or rhymed prose; the intention to magnify something, or departure from the literal expression to belittle it; and other purposes sought in speech. These are the words of Abū al-Hasan al-Āmidī in his major work, the most distinguished of the works by later scholars defending this distinction.

This argument can be answered in several ways.

First:

The usages you mention are not disputed. However, your statement that these terms must be either literal or figurative is valid only if the division of speech into literal and figurative has been established. Otherwise, someone may dispute your position and say:

“You have not given an intelligible dividing line between literal and figurative usage by which one can be distinguished from the other. I ask you to state this distinction between the two categories.”

Or he may say:

“There is, in fact, no definite distinction between them.”

Or he may say:

“I do not affirm the division of speech into literal and figurative, whether because of a rational or scriptural objection, or for some other reason.”

Or he may say:

“It has not been established to my satisfaction that speech is divided into these two categories, or that such a division is admissible in language, revealed law, or reason.”

If he makes any of these or similar statements, you cannot argue against him by saying, “They must be either literal or figurative,” since placing these expressions in either category presupposes the establishment of