It is because of the human heart that anything at all survived and continues to survive. He goes on to describe two giant legs sticking up from the sand that no longer connect to a body, and next to these trunkless legs is the shattered, decapitated head visage half sunk in the sand.
His wide ranging poetry lives on. But wait!
Surely no one could surpass his greatness? No one elsewhere has noticed or mentioned the echoes of Ozymandias.
Here lies the preacher Zebediah Grey: A pillar, incorruptible, severe; Who suffered not the children at their play Nor tidings but humility and fear. Near them, on the sand, Half sunk, a shattered visage lies, whose frown, And wrinkled lip, and sneer of cold command, So whilst the regular rhythm persists, the pauses, punctuation and enjambment help vary the pace and bring interest for the reader and listener.
And perhaps Shelley means to instruct us that art is the highest and most durable manifestation of the human heart.