24 Elders

The 24 Elders mentioned here appear to be human beings clothed in white garments and wearing golden crowns on their heads (Rev 4:4).

They are not likely angels, because angels have never been accorded the title of elder nor seated on a throne. It should be noted that some angels have been given a crown (Rev 6:2), so symbols of power such as a crown cannot be used as a distinction between angels and human beings.

They are not raptured saints, because rapture has not occurred yet. Rapture occurs at the seventh trumpet (Matt 24:29-31) when Jesus Christ returns (Rev 14:14-16), and the seals have not yet been broken.

The 24 Elders seem to play a significant role in Revelation. They mark the moment the seals are to be broken, the seventh trumpet, and when God's wrath is about to be dispensed through the bowls of judgment.

They worship God and cast their crowns before Him (Rev 4:10).

They worship Jesus Christ and praise Him for having the ability to take the book to break its seals (Rev 5:8-9).

They worship God when the seventh trumpet heralds Jesus Christ's second coming (Rev 11:15-17).

Just before Jesus Christ makes the dramatic entrance of His second coming, the multitude in heaven praise God for the righteousness of His judgment, and the 24 elders fell down in worship of God affirming their praise (Rev 19:4).

Aside from the above observations, there isn't enough information that can lead to the identification of the 24 elders.