Clay=Dust+Water

Clay, on the other hand, is dust plus water.

Making the substitutions, we find:
Clay=Dust+Water
Dust=Man
Water=Spirit

Therefore:
Clay=Man (dust) + Spirit (water)

Clay (literally dust + water) is metaphorically man + Spirit. Clay is soft, pliable and moldable.

When he had thus spoken, he spat on the ground, and made clay of the spittle [dust+water], and he anointed the eyes of the blind man with the clay... John 9:6

Nay but, O man, who art thou that repliest against יהוה [Yahweh, our god]? Shall the thing formed say to him that formed it, Why hast thou made me thus? Hath not the potter power over the clay, of the same lump to make one vessel unto honour, and another unto dishonour? Romans 9:20-21

Remember, I beseech thee, that thou hast made me as the clay; and wilt thou bring me into dust again? Job 10:9

Yet now Yahweh, you are our father; we are the clay and you are our potter, and we all are the work of your hand. Isaiah 64:8

The word which came to Jeremiah from Yahweh, saying, Arise, and go down to the potter’s house, and there I will cause you to hear my words. Then I went down to the potter’s house, and behold, he was making a work on the wheels. When the vessel that he made of the clay was marred in the hand of the potter, he made it again another vessel, as seemed good to the potter to make it. Then the word of Yahweh came to me, saying, House of Israel, can’t I do with you as this potter? says Yahweh. Behold, as the clay in the potter’s hand, so are you in my hand... Jeremiah 18:1-6

But now, Yahweh, you are our Father; we are the clay, and you our potter; and we all are the work of your hand. Isaiah 64:8

Shall the thing formed say to him that formed it, Why hast thou made me thus? Hath not the potter power over the clay, of the same lump to make one vessel unto honour, and another unto dishonour? Romans 9:20-21

Dry men, either powdery (lacking substance) or hard (lacking flexibility) can be made soft and pliable like clay through the indwelling of the Spirit of Yahweh. By allowing the indwelling Spirit to work within us, we become pliable and willing to be formed however the Potter (Yahweh) chooses.

Clay, then, represents God's individual people on Earth - His followers, those with His Spirit.