Why do spells affect Harry when he is a Horcrux?

Question

I didn't read the books, only watched the movies... so I don't know if my question is legit.

There are a number of examples of Harry being affected by spells in the books, including:

• Gilderoy Lockhart casting a spell on Harry after he fell from his broom during the Quidditch match, turning his bones to rubber.
• Draco Malfoy cast a paralyze spell on him while he was invisible on the Hogwarts Express (and also damaged his face).
• Luna Lovegood cast a spell on Harry's face/nose so it would fix it, which actually hurt him more.

As far as I know, you can't damage Horcruxes with such "low level" magic. That's why all spells were reflected from Nagini and no sign of damage was done to the pendant.

So why was it still possible?

Answer 1

Harry is not a Horcrux.

As confirmed by the following quote from JKR (which I copied from this answer from the one and only @Slytherincess):

"Here is the thing: for convenience, I had Dumbledore say to Harry, "You were the Horcrux he never meant to make," but I think, by definition, a Horcrux has to be made intentionally. So because Voldemort never went through the grotesque process that I imagine creates a Horcrux with Harry, it was just that he had destabilised his soul so much that it split when he was hit by the backfiring curse. And so this part of it flies off, and attaches to the only living thing in the room. A part of it flees in the very-close-to-death limbo state that Voldemort then goes on and exists in. I suppose it's very close to being a Horcrux, but Harry did not become an evil object. He didn't have curses upon him that the other Horcruxes had. He himself was not contaminated by carrying this bit of parasitic soul."
_source

He just has a piece of Voldemort's soul somehow 'attached', parasitically, to his own. The powerful Dark Magic that surrounds a true Horcrux is not present in him: Voldemort never went through that process with him, since this soul-splitting was unintentional. It is this Dark Magic which protects the Horcrux from harm by low-level spells, so there is no reason Harry should be as protected from such spells as the true Horcruxes are. It makes sense that a soul fragment without special magic doesn't have any special protection; part of the magic involved in creating a true Horcrux must be to create such protection.

From the Muggles' Guide to Harry Potter:

A soul fragment bound to an object, a Horcrux, is proof against ordinary magic, even magic as strong as that produced by an extraordinary wand. (At least, evidence is that Dumbledore believed so, and we have seen nothing against that.) The soul fragment within Harry is not actually bound to him, but is merely clinging to his own soul, and as such is only as strong as Harry himself; if Harry's soul is separated from his body, the soul fragment is detached and vanishes.

Answer 2

I agree with @rand al'thor. Harry is definitely not a horcrux. Although I'm sure your reason from this Rowling person is fine, I have a different reason for this belief.

First, I would like to clear up that a Horcrux is defined as a piece of someone's soul attached to an object, as Slughorn says:

"A Horcrux is a word used for an object in which a person has concealed part of their soul."

That's an object. Not anything else. Living Horcruxes are possible, like Nagini, but for them, the soul is a Horcrux--attached to the body--the object. Whereas in Harry's case, the fragment of Voldemort's soul is fixed to his soul, not his body, just like Dumbledore says:

"...on the night Lord Voldemort tried to kill him, when Lily cast her own life between them as a shield, the Killing Curse rebounded on Lord Voldemort, and a fragment of Voldemort's soul was blasted apart from the whole, and latched itself onto the only living soul left in the collapsing building.

(emphasis mine)

So the fragment of Voldemort's soul is attached to Harry's soul, not his body. He is not a Horcrux.

To answer your question, the Horcrux defense mechanism will therefore activate only if harm comes to the soul, like Avada Kedavra or something. If harm comes only to the body, the soul is unharmed.

"Look, if I picked up a sword right now, Ron, and ran you through with it, I wouldn't damage your soul at all...whatever happens to your body, your soul will survive, untouched."

Thanks to Hermione, we can conclude that whatever physical harm comes to their body from any spells you may be thinking of, the soul will be fine, and therefore the Horcrux mechanism will not trigger.

Answer 3

Harry didn’t have the protective enchantments a Horcrux would.

Horcruxes don’t inherently repel spells because they hold a piece of soul in them - the wizards who make them have to put protective enchantments on them to make sure they don’t get destroyed.

“So does it say how to destroy Horcruxes in that book?”

‘Yes,’ said Hermione, now turning the fragile pages as if examining rotting entrails, ‘because it warns Dark wizards how strong they have to make the enchantments on them. From all that I’ve read, what Harry did to Riddle’s diary was one of the few really foolproof ways of destroying a Horcrux.”
_{^{- Harry Potter and the Deathly Hallows, Chapter 6 (The Ghoul in Pyjamas)}}

It’s not the piece of soul that makes Horcruxes so resistant to damage, it’s the additional protective enchantments that are put on them that makes them so difficult to destroy or damage. Harry had a piece of soul in him, but he wouldn’t have any of the protective enchantments that’d usually be put on Horcruxes, so he wouldn’t repel spells like Horcruxes do.

Answer 4

The horcrux inside Harry only seems to react to protect itself. Also, as the horcrux is part of Voldemort it probably doesn't care if Harry gets hurt.

In the book the ghost Dumbledore says that there is a special magical connection between Harry and Voldemort that allows Harry to do magic he shouldn't be able to do. But the only time this connection activates is when Voldemort is trying to kill Harry. This is because the horcrux in Harry is Voldemort protecting himself, from himself.