Obviously God is not a sibgle-bodied God if He is the Holy Spirit.
The Holy Spirit is not an angel, nor is it a man. It is of the essence of God.
Numbers 11:25
Then the LORD came down in the cloud and spoke with him, and he took of the Spirit that was on him and put the Spirit on the seventy elders. When the Spirit rested on them, they prophesied, but they did not do so again.
2 Samuel 23:2
"The Spirit of the LORD spoke through me; his word was on my tongue.
The Holy Spirit of the Old Testament is the exact same Holy Spirit in the New Testament.