Let’s focus on your last statement for a second, because I think it really gets at the heart of the issue. You’ve positioned yourself as the arbiter of which distinctive traits are sufficient to differentiate halflings from humans to a satisfactory standard. Apparently supernatural luck, courage, tenacity, nimbleness, physical differences (size, body proportions, pointy ears, walking speed), stealthiness, a tendency to blend into the background, a love of creature comforts and cozy places, a tendency toward open-mindedness and being welcoming, and the various other traits that have been mentioned in this thread and/or the source material don’t pass muster for you. Fine, that’s your prerogative. Apparently, a similar list of differences between goats and horses does meet your standards. Okay, no problem.
The issue is how you’ve presented these subjective judgments as the objective truth, when they’re nothing of the sort. You keep insisting that we have some kind of burden to refute your assertion that these differences aren’t good enough, as if it’s not just a matter of differing preferences.
I've positioned myself as having an opinion, yes. I think my opinion is right, because I support it with evidence. And whenever someone decides I am wrong... they just say I am wrong and don't really support their points with anything at all.
Supernatural luck is a differentiating factor (note that "supernatural lucky" is different from "lucky") however it is incredibly hard to actually play supernatural luck in a game like DnD. Sure, I can narrate any misses as "luck" or I can narrate their successes as "luck" but that is just a thin coat of paint over the game.
Courage? Tenacity? Love of Creature Comforts? Open-Mindedness? Welcoming? "various other traits"? Those are all personality traits. And, man, out of a list of about 11 traits, that is 6 of them. So half of what you listed is purely personality. Do I no longer have a halfling if they prefer sleeping in the dirt and don't like strangers? I would certainly hope not. I would hope that I could play a dwarf who likes his creature comforts, is welcoming to all people, and has courage and tenacity. That's why I find these traits weak for the race, if there was more like there are for some of the other races, then it would work better. Or if it worked deeply into their culture and/or mechanics. But other than resistance to magical fear, none of these traits actually come up in halfling mechanics, and with them being pastoral farmers who want to avoid trouble by avoiding notice, then their courage and tenacity rarely shows up.
Then we come to nimbleness, stealthiness, and a tendecy to blend into the background (also known as stealthiness). You know, I got to thinking about this, and this is only a sort of? Yeah, they get +2 dex and this makes them more nimble and more stealthy and better at picking pockets, but that's something that is easy to replicate in dozens of ways. So true, but is there more than just +2 dex? Well... not as much as I think people think. Halflings baseline can just move through an enemies space. That's it. No special bonuses to being stealthy. The only stealthy ability comes from lightfoots, who can hide behind creatures. Which, is a cool thing, and I'd take it... except that it completely cuts Stout Halflings out of the equation. Why are we ignoring them when describing halflings? Poison resistance has actually not come up once as something people attribute to halflings, but it is half of all halflings. It reminds me of when people were going on about how everyone forgets about Forest Gnomes when talking about gnomes.
And then "physical differences". Which is almost all "they are short" but you added a weird one in there. Pointed ears.
To my understanding, halflings had rounded ears, so I started looking it up and you were right... but it led to something interesting. Can anyone tell the gnome from the halfling?
And it is especially amusing because I avoided the images that I saw showing up in both image searches