There are five major divisions of the book of Revelation:
First comes the introduction in chapter 1. Then, chapters two and three address the specific behaviors God wants each of the seven churches to deal with. Chapters 4, 12, and 17 each begin new sections, all saying the same thing but each with a little more detail. Chapters 4 and 12 both begin with scenes in heaven.
Perhaps you will remember the movie The American President where president Andrew Shepherd (played by Michael Douglas) tells Sydney Ellen Wade the Oval Office was designed to intimidate foreign dignitaries. I’ve visited the Oval Office several times (after hours, guided tours) and while is was not originally designed with intimidation in mind, it is definitely impressive.
The scene in chapter four is that of God’s “Oval Office,” though it is usually referred to as the “throne room scene.” Its depiction is without doubt designed to impress. In the ancient world, you would expect the presence of aged advisers (elders) and you would expect it and the presence of the king to be breathtaking. That’s exactly how John depicts it. Don’t get lost in the imagery. You will see something similar in Ezekiel 1, and another description in Hebrews 12. You have, in chapter four, come into the presence of God.
Who are the four living creatures?
We do not know, except that they are to strike awe in the minds of the readers. The creator of heaven and earth might not be expected to have normal attendants. The elders are not just esteemed advisers. They represent kings, all of whom bow before God, and everyone confesses the worthiness of God because He is, after all, the creator of all things.