Yes; law of identity, an object is itself; humans are humans; you are yourself.
I get what your saying though, there are autonomic processes that we have little control over (unless we're one of those people who truly train to be in control of them). That doesn't necessarily mean that we are not ourselves, or even that which we have no control over is not part of us.
Take a machine for example. A machine is not in control of the it's processes, in fact a machine does not even possess a consciousness to be aware of its own existence. We still however say a machine is a machine.
For the babies part, their bodies are able to maintain and keep them alive on one condition, the body receives energy (and is relatively healthy). If you don't give a baby energy, it just won't grow, and die. If you give a baby energy however, there are, as you put it, 'forces' within the body that keep it alive, and make it grow; DNA enables this more or less homogeneous growth between all humans (unless there's a mutation, or difference in DNA).
To say that the body has another force guiding it is a weird question in my opinion. Our bodies are subject to the laws of chemistry, physics, and so on. All these laws affect our body, and our bodies cannot deviate from such laws (our bodies can't suddenly turn carbon dioxide into ATP for example, it's just chemically impossible). Our body has adapted to work within these laws, and the environment around us; we evolved from very simple unicellular organisms. So, to answer the question, the force that guides our bodies are the laws of physics and chemistry for which our bodies have evolved to utilise to its advantage.
Are we separate from our bodies? Well, no. The human is an entity, and it really is the sum of its parts. The body merely refers to the totality of all these parts, hands, arms, chest; it should be noted that the aforementioned forces are not part of this, rather, we are simply governed by it; our bodies obey it.
Our bodies do not always obey instinct. Instinct is not a law, you can go against your instincts. I'd say however that evolution can explain our instincts; we do not have the same instincts as fish for example, because we diverged in our evolution long ago. I'm sure DNA and evolution accounts for most of instinct. That said, since humans have free-will (unless you wana get philosophical on the most vexatious subject IMO), it is theoretically possible for us to go against our instinct (if you're talking about instinct, the gut feeling as opposed to fixed action patterns).
As for the brain, I have no idea, you'd have to ask a neuroscientist. I do think it's a slight misconception though, we consciously activate neurons in most of our brain, just not all neurons simultaneously.
