When we think about thinking I think we're thinking more about the logical way computers process information and less like the emotional way humans do it.
When humans think, we are doing what evolution taught us to do -- keep our bodies whole, fed, warm and sexed. Evolution made us that way. I can't think of a single thing I do that I call thinking that isn't somehow explained as making myself a more attractive sex partner. Everything is motivated by and revolves around the evolutionary goals. Now, what kind of sense does it make to create a machine that's always trying to get laid?
We don't know enough about ourselves to make a piece of software that does what we do. How much of an external perspective do you have of the way your own mind works? And you have access to all the information there, theoretically, i.e. you can read your own mind. Personally, I only have the slightest inkling of how my mind works, what makes me want to write an essay one day and write software another. Yet some days I write prose and other days I code.
I might have a slightly better idea of what other people are like, because I can better observe their behavior from an external standpoint. But as a software developer, you have to fully understand a process before you can write an app that repeats it. We are very far from this kind of understanding of the human mind.
And what of the "sense of self" that's required to make a machine think like a human? How real is that, or is a strong sense of self just another survival trait? Animals that felt their minds are real would fight to continue the illusion. Animals that didn't feel alive would have no reason to fight, and therefore would be less likely to survive to reproduce. It's really possible that this thing we experience as consciousness is actually just an evolutionary survival trait.
If you believe, as I do, that the mind was fully shaped by evolution, that every aspect of what we do and think is a survival trait, then again there's no point creating a machine that behaves human, because our survival programming has become obsolete. Our goal as a species was to overcome nature, to produce so many human babies that enough would survive childhood to reproduce. The humans you see today are the ones who were most fit for the world we, as a species, grew up in, and are now in the process of destroying.
We've run out of time on that path. We have to come up with an approach that reverses the process. Instead of building more cities with car-driving resource-consuming humans, we have to go in a direction that's opposite to our nature. If anything, if we were sane as a species, if we were going somewhere other than oblivion, we would develop machines that were the exact opposite of the humans that evolution created. If we are to create intelligent machines, they should be anything but human in their intelligence.