Ruach is translated as "wind" in the Old Testament. Here, the Greek word is pneuma, which is the equivalent of the Hebrew ruach meaning "an invisible force or power." The illustration refers to wind. A person cannot see air, but it is real, is it not? Its molecules can be packed so solidly, so close together, that they will lift a huge airplane right off the ground. One cannot see the molecules, the atoms, the electrons, or protons, but they are there. We deal with other invisible forces or powers, like electricity and light, on a daily basis, and they certainly exist.
That is the gist of the meaning of spirit. No one would argue that air, of which wind is constituted, is not real, and though it is invisible, it is made up of particles too small for the unaided eye to see. The Bible provides ample evidence to prove that God and angels are not universal nothingness floating around in nowhere. God is not universal mind, conscience, or goodness. He is not an abstract power filling the whole of space. Except for the vast differences in power and potential, the only difference between humans and God is that mankind is earthly flesh and bone whose life is in the blood, while God's body is also flesh and bone but composed of Spirit and immortal.
This has practical ramifications that must be explored because it means that God cannot be omnipresent in the body. The Bible's consistent description of God shows Him at one place at one time, and He is generally seen managing or participating in His creation. We see Him sitting, standing, walking, talking, eating, drinking, commanding, etc., in specific locations. Nowhere is there any mention of God's size, and therefore the conclusion must be that He is of ordinary, human size, and when He became a man, the Scripture says, there was nothing notable about Him except His character and His powerful teaching.