Who first decided to melt the rocks and get the iron?
How do I know? I would have been that guy.
Metal work also started with softer easier to melt metals from much purer near surface veins and worked outwards toward harder less pure more deeply buried metals.
Ready to work gold nuggets are what they are and are rarer to find.
Metal work evolved with mining, chasing surface veins back, and this started in a significant way for first lead|copper, then tin, then other metals.
There's a recognised pre Bronze "Copper Age", then Bronze, then Iron.
Gold is shiny, beyond that it has a limited utility until the age of electronics; it's a bit soft for weapons or armour, a bit rare for sealing pipes, a bit non reactive for easy chemisty^H Alchemy, etc.
Lot's of fun for decorations.
Who, aside from yourself, actually mentioned "throw stuff into the fire for the lols". ?
"Inside the furnace, carbon monoxide from the incomplete combustion of the charcoal reduces the iron oxides in the ore to metallic iron without melting the ore; this allows the bloomery to operate at lower temperatures than the melting temperature of the ore."
and
"As a bloomery's size is increased, the iron ore is exposed to burning charcoal for a longer time. When combined with the strong air blast required to penetrate the large ore and charcoal stack, this may cause part of the iron to melt and become saturated with carbon in the process, producing unforgeable pig iron, which requires oxidation to be reduced into cast iron, steel, and iron. This pig iron was considered a waste product detracting from the largest bloomeries' yield, and early blast furnaces, identical in construction, but dedicated to the production of molten iron, were not built until the 14th century."
While we're here I guess we should also point out that glass blowing furnaces don't melt silicon, they dissolve it into a flux of other stuff to make a gooey glob we call molten glass.
The original question posed was "who first decided to melt the rocks and get the iron" .. technically the rock was smelted not melted in order to remove the rock and get the iron.
The first quibble was that iron isn't melted out, my response was that a bloomery is used instead, my bad for not clarifying that they are used to smelt and not melt.