I don't take it as a three part list of creating characters, providing rules, and guidance
"The Player's Handbook is divided into three parts. Part 1 (chapters 1-6) is about creating a character, providing the rules and guidance you need to make the character you'll play in the game."
I take that as Part 1 is about creating characters. This involves providing the rules and guidance for doing so. I don't take the inclusion of guidance as redundant, but as saying there is advice separate from rules.
For example on Page 8 (still in the intro before Part 1)
"You can think of an adventure as a single episode of a TV series, made up of multiple exciting scenes."
This seems more like guidance as advice or suggestion than synonomous with rules text.