The legal system is not like a computer program. The line between what is "creative" and what is not concrete, but is instead up to the interpretation of the judge who rules on it.

So your phonebook modifications may or may not be considered "creative" depending on the judge and your ability to convince them. The more your modify it, the more likely you are to convince a judge it is a creative work, though.

It would depend on how transformative the work is.

There is in fact a whole art form where people cut out words from different newspapers and books, for example, and re-arrange those words to form new and interesting art.

So there are ways in which such a work would be a creative work, and ways it which it would not, and it would depend on the particular instance and example.