There really are two options: angels or people. The following arguments point to them as being people.
Angels are
ministering spirits sent out to serve for the sake of those who are to obtain salvation
(Hebrews 1:14; see further Psalm 103:21). Being enthroned does not fit well with a task as servants. Nowhere else does the Bible describe angels with the termelders
.Paul had written that saints who once were dead in sin have been raised with Christ and made to sit with him in the heavenly places (Ephesians 2:6). Jesus had also spoken of faithful servants receiving positions of authority in his kingdom (Matthew 19:28; Matthew 25:21, Matthew 25:23; Luke 19:17, Luke 19:19).
Though we certainly cannot put names to these twenty-four elders, we may conclude that already the Lord has elevated saints of previous generations to some sort of heavenly thrones. These twenty-four elders, then, were keenly aware of the weaknesses that beset God’s people/churches on earth (Revelation 6:10).
4 Around the throne were twenty-four thrones, and seated on the thrones were twenty-four elders, clothed in white garments, with golden crowns on their heads.