The four living creatures represent the whole of creation because their biblical symbolism (lion, ox, man, eagle) points to the great categories of the created order, and because Revelation places them around the throne as figures of universal worship.
Biblical origin
Ezekiel 1 and 10: the four living creatures already appear in the prophet’s vision, each having the faces of a man, a lion, an ox and an eagle. Ezekiel identifies them as cherubim, linked to the throne of God.
Revelation 4.6-8: John takes up this vision but simplifies the figures: a lion, an ox, a man and an eagle. They are placed “in the midst of the throne and around the throne,” and sing unceasingly: “Holy, Holy, Holy.”
Symbolism of the four figures
Lion: strength, kingship, animal power.
Ox (or calf): fertility, service, domestic power.
Man: intelligence, reason, spiritual dimension.
Eagle: sky, height, vigilance, swiftness.
These four figures cover the great spheres of creation:
Wild animals (lion),
Domestic animals (ox),
Humanity (man),
Winged/celestial creatures (eagle).
Theological interpretation
Universal worship: their presence around the throne means that all creation is included in the praise of God.
Cosmic vigilance: their eyes “all around” symbolize vigilance and universal knowledge.
Patristic tradition: the Church Fathers (Irenaeus, Jerome) saw in these four living creatures not only creation, but also the four evangelists, each reflecting one facet of Christ.
Synthesis
The four living creatures represent the whole of creation because:
Their symbolism covers the main categories of the created order (wild, domestic, human, heavenly).
Their position around the throne directly associates them with universal worship.
Revelation does not separate theology and cosmology: salvation concerns the whole of the created order