This question got me thinking could muggles in the harry potter universe survive without wizards, if wizards died out for some reason perhaps every newborns is a squib, what would be the effect of this on the world of Harry Potter ?
I'm imagining that giants, dementors and the like would run amok ?
Would House elves take it upon themselves to protect the muggle world ?
I've found something that can explain how the Muggles are/were protected from the magical beings like dragons and dementors and such...
Can't believe I'm actually typing this but; in 1750, Clause 73 was added to The International Statute of Wizarding Secrecy. Here is the mentioned clause:
Each wizarding governing body will be responsible for the concealment, care and control of all magical beasts, beings, and spirits dwelling within its territory's borders. Should any such creature cause harm to, or draw the notice of, the Muggle community, that nation's wizarding governing body will be subject to discipline by the International Confederation of Wizards. —Clause 73, International Statute of Wizarding Secrecy
So, the wizarding community was under obligation to protect the muggle community in order to stay hidden and safe.
It is a very necessary clause but it's been breached repeteadly.
There is no need to say that if the wizarding community didn't bother to protect muggles, muggles wouldn't survive. Not only the magical creatures would annihilate them but wizards like Malfoys and Tom Riddle would also try to erase them from existence.
There is no definite answer to that possible, I think.
However, in my opinion, the impression I form from the books is that magic, while basis of the wizarding world [which in itself is a rather small in terms of quantity of wizards] was not that easily seen in the mundane world, except when dealing with the result of miscalculations or malice by wizards.
If we consider what we see described about Arthur Weasley's work, it is mostly to do with amok spells or magical items created by wizards. Yes, there are mentions also of wild magical creatures accessing mundane world, however, my impression was that just like ordinary animals, magical animals are more frequently avoiding humans.
And, starting from the second half of 20th century, and moreso now, I think, if magical creatures were not subtle enough, any massive outbreaks of attacks on humans would provoke investigations and some sort of mundane dealing with the magical problem, simply due to (population) size differences.
Dementors or other indirectly harmful magical beings might be subtle enough to affect lots of people without noticing, however, if we consider depression as magically induced, while substantial portion of people are affected by it, it is not as if we are completely helpless about it.
Additionally, while any particular magical creatures might be immune to some sort of human weapons (bullets, etc.), none of them in the JKR world seem to be immune to EVERYTHING.
I feel like the muggles wouldn't survive without wizards in the Parry Potter universe, because wizards are known to be secretly helping them anyways. If we took wizards away from that universe, there would most likely be Chaos. From all the deadly magical things that walk the earth.
