What do the four living creatures represent?

Question

From Revelation 4 (KJ21):

⁶ and before the throne there was a sea of glass like unto crystal. And in the midst of the throne, and round about the throne, were four living beings full of eyes in front and behind.

⁷ And the first being was like a lion, and the second being like a calf, and the third being had the face of a man, and the fourth being was like a flying eagle.

⁸ And each of the four living beings had six wings about him, and they were full of eyes within; and they rested not day and night, saying, “Holy, holy, holy, Lord God Almighty, who was, and is, and is to come!”

What do these four living beings represent?

Answer 1

They represent the Tetramorph, the 4 classical elements in the West. More info:

A tetramorph is a symbolic arrangement of four differing elements, or the combination of four disparate elements in one unit. The term is derived from the Greek tetra, meaning four, and morph, shape.

In Christian art, the tetramorph is the union of the symbols of the Four Evangelists, derived from the four living creatures in the Book of Ezekiel, into a single figure or, more commonly, a group of four figures. Each of the four Evangelists is associated with one of the living creatures, usually shown with wings. The most common association, but not the original or only, is: Matthew the man, Mark the lion, Luke the ox, and John the eagle. In Christian art and iconography, Evangelist portraits are often accompanied by tetramorphs, or the symbols alone used to represent them. Evangelist portraits that depict them in their human forms are often accompanied by their symbolic creatures, and Christ in Majesty is often shown surrounded by the four symbols.

Source: Tetramorph (Wikpedia)