Gold is found in its purest form as golden nuggets, it is shiny and aesthetically pleasing. It was easily found and identified in the surrounding environment of rocks and gravel due to its bright yellow-ish colour and lustre. Which was then used in jewellery during the Stone Age.
Copper was discovered at around 4200BC but nobody knows for sure. Copper did not require deep excavation in order to access the ore and was found in the natural environment, leading to its easy discovery.
Silver was discovered quite easily in the form of nuggets and rarely in large pieces. They were naturally occuring in minerals and sometimes in rivers, They were easily identified as the shiny lustre attracted people in minerals and led to its eventual discovery.
A theory suggested that the discovery of bronze was accidental, as the ancient Sumerians used copper and tin-rich rocks at campfires. As the temperatures rised the metals melted and mixed; creating bronze. Nobody knows for sure who or how exactly bronze was first formed.
Lead was easily found embedded in ores like Galena. The lustrous and the shiny rock was easily found as it caught the attention of people easily in minerals. They were found near ground level, requiring no deep excavation and was found relatively easily.
Tin is usually found in ores such as cassiterite, it's lustrous and shiny which would be easily spotted when mining, as people did not need to dig too deeply in order to find them.
Iron is a highly reactive metal in oxygen which could have been a factor to it's later discovery, iron was first found in the form of iron meteorites that people in the past have collected and examined, and upon closer inspection found metals that they could smelt and use in tools, weapons etc.
Ancient metalworkers often created bronze smelting copper and tin, sometimes creating brass unknowingly as zinc and tin were usually found together in ores, sharing similiar appearances and properties. Once zinc could be distinguished.
The discovery, or rather the creation of steel goes way back to 300BC where craftsmen in Southern India had used crucibles to smelt iron with charcoal creating 'wootz' steel. This process was later standardized and mass produced by Sir Henry Bessemer.
Although Greeks and Romans used aluminium salts, metallic aluminium was not used until the modern day. Danish physicist and chemist, Hans Christian Ørsted, he reacted anhydrous aluminium chloride with potassium amalgram and created a lump of metal that resembled tin, and had not been properly named Aluminium until after the experiments. As well as this, aluminium is one of the most abundant metal in the Earth's crust, whilst not occuring naturally, it would be found and discovered easily in mines without extremely deep excavation.