Iron is in the first tier. It’s not very exciting. It’s a base resource required to craft other items or, if you’re in desperate need of one-time protection against a late game evil boss, it can be hammered down into masses of iron bars to generate 50 ingots and 10 blocks.
Iron ore along with copper ore and tin ore block will give 3 times as many materials when smelted until they are depleted for silicon ores. The second tier is tin then zinc then lead for the 3rd tier. Lead alone has little use but combined with any of the metals from 1st tier will create bullets that do more damage when used on bosses via guns crafted using metal from tiers 1&2 each.
Tungsten is the 4th tier resource. It, alone, has no use other than being a component of alloy metal bars that have twice as much durability as iron bars. Crafting those alloy bars requires a few shapes and sizes of coal ore blocks, silver bars and tungsten or titanium ores. The 5th tier metal is titanium. This metal is required to craft the jetpack which, in turn, is needed for exploring and collecting some of the rarer gems and ores like gold and titanium.