The beasts are not representative of redeemed human beings, because they don't join in the Redemption Song. Revelation 5:8-10.

       The word 'they' do not refer to the 'Four Living Creatures,' but to the 'Four and Twenty Elders.'

              The Four Living Creatures are not in the same class with the Elders, they have no
                  thrones,
                  or crowns,
                  or harps,
                  or golden vials.

They are guardians of the Throne of God.