Q: Are we human beings merely machines?
A: I don't like your expression "merely" machines. You see, all things are machines. And why? Because everything works by cause and effect, which is a mechanistic process. That which works mechanistically is a machine.
Q: There are some things which do not work mechanistically.
A: Name me one thing that happens without being caused to happen! You cannot do it. You may be able to cite me cases where you are unaware of the cause, but it is absurd to suggest that anything can be without a cause.
Q: Looking at our situation from the genetic perspective, are we merely survival machines, robot vehicles blindly programmed to preserve the genes? Is reproduction our primary purpose?
A: Your question implies that the mind is but a tool of the body. It can equally well be argued that the purpose of mind is to preserve the mind - that the mind is the purpose of reproduction, rather than the other way around. What came first, genes or mind? The answer is neither and both.
Q: That raises an interesting question: what is the mind? Is it in the brain?
A: That in turn raises another interesting question: what is the brain? It is assumed to exist in the skull, but when we try to find its beginning and end we are confounded. We discover that the brain is inseparable from the body, which is in turn inseparable from the environment in which it lives. Now where is the mind?