Why is the Spirit the "Spirit"?

Why is the Spirit of God called the "Spirit"? I've discussed this before, but I'd like to be a bit more discriminating this time. Seems to me that "ruach/pneuma" trades on several connotations, all of which are germane to this member of the Trinity:

1. In Biblical usage, a spirit is:

i) A personal agent

ii) A discarnate agent

So one reason for the designation is to indicate both the personality and incorporeity of the Spirit. The Spirit is not a power or force. And the Spirit is not a physical being like the humanoid gods of the heathen pantheon. Put another way, Yahweh is incorporeal. 

In this regard, the designation connotes the essential identity Spirit. The name has a metaphysical or ontological connotation. 

2. It has life-giving connotations. The breath of life. So the name indicates that the Spirit is the source of biological life.

3. Apropos (2), by extension, it also connotes the Spirit as the source of inner renewal or regeneration. Figurative life as well as  biological life.

4. Finally, it has connotations of divine speech. The spoken word is breath. So it signifies the role of the Spirit as the source of inspiration, revelation, and agency of Scripture. 

In that regard, the designation connotes the economic identity of the Spirit. The name connotes his creative and recreative activity in the world, as well as his revelatory role.