As for "copying", even copies can be quite extraordinary.
http://www.evoke.ie/photograph-of-an-old-guy-no-this-picture...
Art is easy because life is easy.
I've always gone by the idea that art is all just communication of some kind. There is a speaker, an audience, an idea sent, and an idea received. The exact idea received will never be exactly the same. It is always dependent on both the speaker and the audience, and how much shared culture they have. Art is fundamentally a fractal. It is the use of bits of culture to express new bits of culture.
Even people who say, "It means nothing" are saying something. They're saying, "your never-ending search for meaning in the world is inherently meaningless". Because if the artist never wanted anyone to interpret their work, they would never show it.
Art is not just for artists.
Similar to how Leibniz and other pantheists said God was everywhere, but this meant God had a different denotation that what everyone else thought when they heard the word 'God'.
Also, if I create a work that I immediately destroy and not tell anyone about, or give a private performance no one sees, did art not happen?
Your examples of a telephone book, a traffic signal, a TCP/IP packet, are interesting, because these are all things that, in their specific form are not made by a person, which fails on my first criteria. They're made by machines. However, the infrastructure in place to provide them was made by a person. And I would absolutely call the telephone system, the highway system, or the Internet a work of art. I don't think that's even controversial.
I had a friend that literally this is what he wanted. He wanted to to be told what was and wasn't art, what was good and what was bad art, so he could know what he should be spending his time and money on. Emphasis on had a friend, he was a dolt in a lot of other ways, we don't hang out anymore.
"Not everything can be art!" He would say. Why not? Really, who gives a shit? Why did he care that some things should not be art?
Art is fundamentally in the personal reaction, just as much as it is in the delivery. The two are inextricable. A rainbow is not art if you don't believe in God, but it is if you do.
I consider art appreciation to be an important step in becoming a well-adjusted, tolerant human being. You have to learn to know what you like, and why, and you have to learn that others won't agree with you. THAT'S why people refuse to define art, because they don't want others defining it for them and don't want to be found guilty of the same sin. Because it's in the personal reaction as much as the delivery.
So by that measure, no you can't (and I don't mean shouldn't, I mean it is physically impossible) to call something you've kept to yourself "art". The word "art" is itself a communication of an idea. To call a painting you burn before you let anyone see it, a dance you do in the mirror, a song you sing in the shower, is to attach meaning to it, and meaning is for the purpose of communication. At that point, if you do communicate it, you've performed it in some form. Perhaps the art is your retelling of how skillfully you masterbate. Or perhaps the person you are communicating to through your journal is your future self--who is himself of a different, more experienced, though shared cultural background, as present day you. Its artness is made in the transmission of the idea, and immediately so.
You might be familiar with the Fluxus movement in art; if not, you might find some of their ideas interesting too - http://en.wikipedia.org/wiki/Fluxus
There's very few things that won't make you feel something if you choose to look at them. By that I mean we ignore all kinds of stuff in our day to day lives but pull out any one thing, a spoon, a rock, a front door, a crumpled can, a beer, decide to pay attention to it and you'll feel something.
I don't have a better definition, all I'm saying is I could make an exhibit taking the next 50 things I see and just displaying them. Some would call that art. I'm sure they'll be a big debate about how collections are art, the act of creating an exhibition is art, etc. That's not really the point I'm trying to make. Rather it's that if I can pick up literally ANYTHING and display it and it magically becomes art that's not a really useful definition, at least to me.
As an example of your kids' mess, check out Tracey Emin's 'My Bed' [1], it's basically just a mess, but by deciding it is art and exhibiting it for that purpose it becomes art. But when it was in her house in the exact same state.. not art, as it wasn't intended to be.
It's important to remember though that confusion is not an emotion.