@maxdancona,
I believe that the pre 1000BC Ferrous smeltig was an independent vent, why, because the available ores ar quite ubiquitous. Ores come in all kinds and Sub Saharan Africa is full of all of them'. Iron iisnt the big techno advnce. It could be made by accident just like bronze and iron's properties arent any better than bronze. NOW STEEL!!! , thats your real toolmaker.
Iron was easily made by:
Laterite clays are FE /Al clays that have been serving as iron ore into our on colonial times (Nasawingo furnaces near S Eastern Shore of Md had used "red clay" smelted with charcoal . These laterites are all over in Africa within the cratonic sediments
Magnetite and HEmatite sands are along the streams in bed of dense black masses of sands at ,2mm diameters. . These are quite pure ores
The main question isnt that it happened but under what circumstances??
Iron BLOOMERY is where clays or other minerals were incorporated into things like ovens or fire pits and in many cases the iron rich clays or sands were "softened " (not smelted), into masses of dense material called "FAYALITE" ,an iron silicate mix. These were brittle masses of purified (almost a "wrought stage" iron silicate). This was what was called an IRON BLOOM. Not good for much until
different archeologists have dated the carbon wastes in their bloomery samples an came to conclude that several bloomeries were established almost independently of each other.
It then took actual smelting of the fayalite and carbon masses to generate metallic iron called STEEL whixh is one of the hardest metals and is therefore usable in tools and especially points for short spears.
Carbon 14 has had a dubious series of results in African bloomery (mostly due to the corrections required for nuclear Decay within already radionuclide rich forelands. (Africa is still the worlds leader in massive Uraninite(Pitchblende) and other specific uranium ores). C14 is tough in any of these neighborhoods, we still use Luminescence techniques.
Bloomeries could have been established as just good luck when someone was really trying to bake a loaf of bread or make pottery in a kiln made of laterite.
Making iron or steel actually took some thought a to adding clinker rocks or even "spar" to float off the "gangue" (crap). Then someone had to learn how to employ the kinds of blowers like used in Tin and copper smelting to actually melt the steel