Interesting translation by Pervez. Btw, jinn is something/somebody far in space or perception, ie. alien/stranger, and if this is about creatures they're always human, but stranger to the subjects. In surah Jinn (72.) these jinn are talking about jinn (strangers) to them.
In Antic and Middle Ages people knew that dirt is causing food to rotten and can cause illness, since they didn't know exactly why they named it jinn, cause it was out of their perception. Later, when microscope discovered, humans discovered many of these jinn and called them bacteria, fungi, etc.
Theoretically, there could be some creatures we cannot see, since our eyes register only visible light (a small part of light), but I agree that these creatures would have solid bodies, Creatures of fire and air are just myth, since Allah told that He created all out of water, and air and fire cannot be a container for water, only "earth", solid things.
