While its true many weapons become "Mythified" such as the katana able to cut though anything...
The slings accuracy by properly trained slingers(from a very young age) is documented by actual historical records.
Greeks used them as snipers to kill enemy commanders in the center of a battle from outside edge of battle.
You claim this is propaganda..
Yet
Spanish records state that the Pacific islanders slings out ranged the effective range of the firearms the Spanish had(smooth bore) and were capable being slung with such force they would bury themselves in a coconut trees and they fired far faster.
The British empire in Afganistan reports that it was not the Bows or firearms that were the most dangerous weapon the Afganis had... it was the sling.
We have actual documented historical records of firearm using troops vs competent slingers, which if anything would want to DOWNPLAY the effectiveness of such a primitive weapon... and also from personal letters not public.. so once again.. little point for propaganda.
We also know that the slings POWER and RANGE were not propaganda... as they are easy to reproduce.
It seems weird to me that people would feel the need to overstate the accuracy of such weapons, the Spanish for example with the Aztecs state they were NOT accurate with them yet they used large stones the size of your fist or bigger and could kill a man or horse instantly, in this case the slings were more artillery then pinpoint weapons.
Its easy to claim things are myth... we could go that route with longbows and 11 arrows per min.
This was considered a myth.. its now been confirmed by archers that have grown up using longbows at 160-180 pounds... its not a rate that can be continued yet its now proven when previously it was considered myth...
Also it was considered "myth" about stories of archers rapidly shooting arrows, shooting arrows while falling off a horse etc... yet now its known NOT to be myth.
Check out Lars Anderson on youtube.
You may wish to hold off on calling(Or this case imply) things as "MYTH".
The sling holds up in both power and range to historical records, it however falls on accuracy when used by modern "slingers" yet most of these picked it up in late teens or adulthood not trained since able to walk and we also know that technique is important and we actually dont have knowledge of how exactly ancient slingers used slings. No ground exists to argue the accuracy of the sling from historical records when those same records are correct on the range and power while accuracy which is based on experience is the only thing lacking and those same records often mention training since childhood of expert slingers.
Which brings us back to the thread and topic at hand... the Atlatl seems to an easy weapon to build and learn to use with relative effectiveness(something the sling is not).
Having now made two rough versions I have found it really easy to make to the point if need be you dont even need a knife. It beats a bow for ease of construction, and beats a sling for ease of function.
Seems to be the goldilocks of survival weapons.
I would still rather rely on traps to try to catch food, but in a situation I was in need of gathering my own food without a firearm I would also take the time to make an Atlatl.
"The most accurate non rifled projectile weapon humans ever invented" that is a bold statement, even with the "(that we know of)" part.
Well there you go, it must just be another of those things that we can't do today or atleast don't see on the youtube.
I've seen shepherds in Afghanistan throwing rocks at feral dogs, they had the distance but not the accuracy to scare them off but only hit 1 out of 10 from what I saw.
As far as classical Greece, propaganda is propaganda, even if its written in Greek.
all I'm saying is I've seen guys that were suppose to be good with them that weren't that good as far as archery goes.