There seems to be two answers if I google the question. One is that yes Mario is a murder and the other is not on your nelly!
View one seems to be this widely spread and well known theory which has been mentioned in a couple of articles and in the OQ -
5. Mario is an Insane Murderer and Princess Toadstool Couldn't Care Less About Her Subjects
The Horrible Truth About Super Mario Bros -
"But wait!" you argue. "There are people who support the Princess! But they were turned into brick blocks by the evil Koopa!"
First off, don't argue at your computer screen. It will not respond to you. These are pre-written words, dude. You're weirding out everyone in the computer lab.
Second, good point, hypothetical reader! There were untold numbers of denizens turned to brick, at least according to the game's manual, which is a fun weird horrible fact that has become more popular and well-known in these modern internet times of ours. So maybe the noble Toadstool family was looking out for the best interests of the people, but that crooked Koopa got in the way of their benevolent love for the commoners.
Except not at all. For one, Mario destroys everything he possibly can, mostly those bricks. He's rewarded for it. He does it for points, for coins, and sometimes to kill Koopas and Goombas unlucky enough to find themselves beneath the bricks Mario has targeted.** So - Mario pretty much murders the entire population of the kingdom, while at the same time tries to save the oppressive monarchy by crushing as many animals as he can find. Great.
But the best thing of all: reinstating the Princess does nothing, since the bricks continued appearing in Mario games to this day. By now, Mario would have to be aware of the bricks' true nature, but he doesn't care. And the Princess certainly doesn't care enough to bring them back to life either - according to the game's manual, only she has the power to bring the people back, but she never actually does. In fact, the only transformed people anyone ever really changes back to normal form are the kings of each world in Super Mario Bros. 3, while the regular people are left to be destroyed by a chunky plumber in a frog suit.
What a surprise.
And beyond this, the entire theory must come to question - if Koopa really had the ability to turn people into bricks, why wouldn't he have done the same to Mario, instead of jump around and shoot ineffective fireballs at him? Why wouldn't he have done it to the Princess, instead of letting her sit around behind him? This seems like an incredible power to just waste on everyone except the people trying to murder you and your entire army.
But there are also a great number of people that say that he is just the hero of the game -
But also let's look at later version of the story. First, Super Mario All Stars.
The Mushroom Kingdom was a peaceful place, until the fateful day that Bowser used his twisted magic to invade it. Bowser turned most of the Mushroom Kingdom's people into rocks, bricks, and mushrooms. He even kidnapped Princess Toadstool and held her captive in his huge castle.** When the Mario Brothers, Mario and Luigi, heard this, they knew that they needed to do something.** They decided to battle Bowser and his evil minions to save the Princess. Can they do it.
Note, the "field horse-hair plants" were replaced with "Mushrooms" while the rest of the story is pretty much the same.
The story for Super Mario Bros Deluxe is pretty much the same as the original, other than some wording difference, and it too replaces "field horse-hair plants" with mushrooms.
Now, there is one page from the original Super Mario Bros NES manual that everyone other than me over looked for some reason. And this will clear everything up, and you'll see why my blood boils whenever someone mentions Mario killing people.
If you come across mushrooms who have been turned into bricks or made invisible, they reward you by giving you a power boost. With each boost Mario changes into a different, more powerful Mario, as shown below.
Now you see the point of this post. The powerups are the mushroom kingdom citizens, not the random blocks you destroy. That's why it says they were changed into "field horse-hair plants" and mushrooms in later versions. They were changed into Fire Flowers and Super Mushrooms. That's why the power ups always have a face on them. The bricks they were changed into are the mystery blocks or the blocks that give you power ups. I think the blocks that give you coins might be citizens, too, but I don't know. However, these blocks can't be destroyed (Until later games, so maybe there is some truth to this).
I can personally account for this as I have found some of these blocks myself.
It also seems like Nintendo has cleared up what they meant with the Super Mario All-Stars collection for Wii. Or at least made an attempt!
Other changes are more severe, like the description of how one actually plays a Super Mario Bros. After all, everyone knows how to play a Super Mario Bros. game by this point, right? That's what the Wii Super Mario All-Stars manual pretty much assumes. The directions are simple: "Defeat enemies and reach the flagpole at the end of each stage before time runs out! Clearing three stages and a castle stage will allow you to advance to the next world."
The Wii manual has three other Super Mario Bros. games to explain, so its brevity is also understandable.
The NES manual for Super Mario Bros. explains how a video game works in much more detail.
It goes on to say -
The motivation behind Mario's adventure to save Princess Peach—or, as she was known in the NES manual, Princess Toadstool—has also been updated. Did you know that the Koopa turtle tribe was a practitioner of black magic, for example? Yeah, they used it to turn the Mushroom People into field horsehair plants.
This is the story of Super Mario Bros., 1985 edition.
One day the kingdom of the peaceful mushroom people was invaded by the Koopa, a tribe of turtles famous for their black magic. The quiet, peace-loving Mushroom People were turned into mere stones, bricks and even field horsehair plants, and the Mushroom Kingdom fell into ruin.
The only one who can undo the magic spell on the Mushroom People and return them to their normal selves is the Princess Toadstool, the daughter of the Mushroom King. Unfortunately, she is presently in the hands of the great Koopa turtle king.
Mario, the hero of the story (maybe) hears about the Mushroom People's plight and sets out on a quest to free the Mushroom Princess from the evil Koopa and restore the fallen kingdom of the Mushroom People.
You are Mario! It's up to you to save the Mushroom People from the black magic of the Koopa!
This is how Nintendo explains the story of its NES classic for Wii owners.
The Mushroom Kingdom was the peaceful home of the Toads until the day Bowser and his wicked minions invaded. Using powerful magic, Bowser transformed the Toads into bricks and quickly conquered the land.
Only Princess Peach had the power to remove Bowser's curse and save her people. But Bowser kidnapped the princess and hid her in his castle. All hope seemed lost, and darkness reigned...
When the Mario Brothers, Mario and Luigi, heard this story, they decided to rescue Princess Peach and defeat the evil Bowser. Can the brothers save the beautiful princess before it's too late?
So... No, Mario is not?