Before the throne of God there are 24 representatives of mankind. John does not define these 24 persons in more detail.
Their white robes show that they have been washed clean. Revelation 7:14 says about the robes: “They have washed their robes and made them white in the blood of the Lamb”.
The golden wreaths indicate that they have received the crown of victory. They have arrived at their destination.
Paul writes in 1 Corinthians 9:25, “Competitors… do it to receive a perishable wreath, but we an imperishable.”
The golden wreaths, the white robes and the designation “elders”, representatives, chiefs indicate that these twenty-four persons are not heavenly beings but human representatives.
Revelation 4:4, “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.”