Off the top of my head,..Obfuscation, let's see, changing terrain or growing vegetation to block line of sight, hiding path entrances exits or the path entirely, perhaps underground or through tree roots or something. Misdirection, false signage, false pathways, installation of something that draws the eye elsewhere away from the direction of the village or the parts to it. Disguise, various combinations of earthworks and vegetation.
Would they need help, sure. The point is that have the knowledge for how to avoid notice and those skills are applicable.
And you're accusing me of handwaving while apparently going with ever Gnomish village includes an 11th level caster whose illusions are utterly impenetrable
Okay, now we are getting to some ideas.
Most of which seem to involve growing a screen of trees around the entire village thick enough to block line of sight or building hills. Both of which are long, arduous processes that would take decades to finish. And it somewhat ignores some of the issues beyond that.
Let's say that you don't grow a forest around your village, and instead go and build a village in the forest. Sounds much easier right? Well, to get actual farmland you would need to clear out the forest. If I assume a very small homestead of 2 acres per farm, ten families and their houses, looking at close to 50 acres. Which is roughly 50 acres of forest you need to clear. That is a rather noticeable dent in the forest.
And that doesn't make it safe, especially considering that many goblin tribes and other forces seem to find ruined castles in the forest with some regularity, and the largest castle in the world is only 13 acres of land.
Or maybe they have tunneled over a mile underground, to make a small road underground to avoid anyone finding them, but that involves there being no other real way to find the village, like being in a secluded valley between some hills. But... that doesn't do anything if someone happens to go over a hill, or if they go around it to the inside instead of the outside. And, that underground path would need to have an entrance. You could just grow over the entrance with bushes so thing you can't see the cave mouth, not sure how you'd get livestock through it, but that isn't even the bigger problem. You know who tends to find out of the way caves to live in? Goblin tribes.
And, since the underground road isn't visible, you can't see people approaching. So if anyone did find it, they are going to be on top of you before you know anything is wrong.
And remember, this isn't just talking about a single village. We need to extrapolate this for every halfling shire. They all either found or created deep forests and hidden valleys for them to live in, and unless they are deep in civilized lands, those are exactly the sort of places that we tend to find monsters.
Is enjoying tasty food enough to go to war for it in the human write up? I don't see it. Is "exemplar of ambition" in it? Is halflings enjoying delicious food in the write up? Hell, is there a note in the human entry of the PHB about delicious halfling food and their potential if they had ambition?
It seems you're only willing to adhere to the writeup when it's convenient for your argument.
As I said, if you want to change human nature, that is fine, but I am willing to assume that humans in DnD are humans.
The Opium Wars were England companies going to war with China over Tea.
The Exploration of the Americas was because of the Ottomans controlling the spice trade routes, and European powers wanting to get cheaper spices.
The Ottoman empire seemed to partially destroy itself in a war over wine.
Egypt was conquered for grains
Pope went to war over salt, as did a lot of other people at various points in history
Humans could have easily said, "You know, I am content with rosemary and thyme, I don't need cumin and cayene for my food" but we didn't. We fought and died over these things.
Yes, halflings are specifically called out to love food. And humans aren't specifically called out, but I'm willing to bet that humans are humans. And taking the stance that humans wouldn't go forward in cultivating crops that could provide them with spices, when that was literally the biggest driver of trade in the history of the world, and literally reshaped the world as we know it due to the imports of foreign foods, I'm going to say that doesn't hold water.