In chapter four the vision of these dramatic years on earth begins when John is called up to heaven into the throne room of God. God is encircled by twenty-four elders and the four cherubim.
The vision opens with the throne of God presumably in the heavenly temple encircled by rainbow of light and a series of beings. In Revelation 4:6-9 the four living creatures (also seen in Ezekiel 1:5-25) form the first encirclement. They are encircled by twenty-four thrones with twenty-four elders. In Revelation 5:11-13 we see in a larger circle of angelic hosts. There will be yet another group appear in chapter 7:9 of a great multitude of the redeemed from the earth before the throne.
The question that is asked is, “Who are these elders on the twenty-four thrones?” It is usually agreed the twenty-four thrones are seats of representatives of either an angelic or human group since the Old Testament (1 Chronicles 24:3-19) has a clear parallel of twenty-four divisions of Levitical priests who were represented by a single priest. But, who are the elders representing? There are three suggested answers: orders of angels, believers of all the ages (12 tribes from Israel plus 12 apostles), or representatives of the church.
Some clues are given in John's vision. First, their white clothes could be angelic or redeemed men. In 7:14 and 22:14 men are said to have washed their robes. Second, the word translated "crowns" is not diadem, a crown of a ruler with governmental authority bestowed on them, but stephanos, the crown of the victor which was awarded the winner in the Greek games. These "elders" have won a contest and received the award. Third, the "thrones" have already been part of the eschatological rewards promised to the churches by Jesus in 2:10, 3:5 and 3:21.
In addition these elders use golden incense bowls in 5:8 as priests representing the saints. And, in 7:11 the elders are clearly distinguished as a separate group than the angelic hosts.
At this point it would appear that these elders are human believers who have already gone through judgment and have received their reward and are serving as representative of the believers who are still on earth and those who are worshipping in heaven.