Something I don't think people realize about historical weapons and...should be considered in fantasy.
...a properly shot stone from a sling can generate 100ft lbs of force and rival a javelin or spear.
Shepherds had only slings for ages.
They do require amazing skill, but when it's all ya got in the backwoods....you get damn good.
There are recorded quotes from conquistadors that Incan slings were chipping, even shattering, some swords. You take that to the upper 1/3 of your skull? Rip...
David beat Goliath because he brought a 9 mil. To a sword fight.
Now bows overtook the sling because it's an easier skill gap to close than mastering a sling.
Easy? No..still takes practice.
You can also get off more shots quicker, and then when you're mounted??? The Mongol Empire, the largest contiguous land empire, has entered the chat.
But, yeah, slings are gnarly. They're cheap. Effective.
And rocks...well, ammo is everywhere.