Jessie Jackson once read "Green Eggs and Ham" on SNL. That's a unique voice for such a well known story. Watch on YouTube.
Jessie Jackson , Sean Connery, Iced-T and George W. Bush all telling you the same story.
...on what they would tell you would all be different, even though the main points of the story would be the same.
We all have a natural voice and probably a writing voice.
But at times we need to be in the head of our characters, so the reader can feel the difference between the author, the main character, the bad guy and the secondary characters, just by reading the words.
Let’s look at this through a movie context. Spiderman has been played by Tobey Maguire and more recently by Andrew Garfield. Batman has been played by Michael Keaton, Val Kilmer, George Clooney and Christian Bale (and don’t forget Adam West). Granted the directors, writing and scripts were different, but each actor brought uniqueness to the character.
Two other examples are Parker and Jack Ryan. Parker/Porter has been played by Mel Gibson in “Payback” and now Jason Statham takes on the role. Ryan has been played by Alec Baldwin, Harrison Ford, Ben Affleck and Chris Pine. Again, the same characters with a slight difference.
Now take a look at the opposite, Tom Cruise and Keanu Reeves. For most of their roles, they play almost the same stoic character despite the different movies. Such bad acting.
As we write, we must know our characters enough to use the appropriate words, inflections and mannerisms to make them different and real to the reader.