I searched through Genesis trying to find the earliest mention of metalworking in the Bible, and I found it, though only one verse long. It is Genesis Chapter 4, verse 22: ‘As for Zillah, she also gave birth to Tubal-cain, the forger of all implements of Bronze and Iron; and the Sister of Tubal-cain was Naamah.’ As you can read a few verses before, Cain is Tubal-cain’s great-great-grandfather or something like that. Bronze is an alloy of Cu (Copper) and Sn (Tin). From what I understand, metalworking was invented before the flood.
It’s possible neither Noah nor his sons knew any metalworking, so they built the ark, went inside, flood came, flood went, they came out, and no-one knew how to work metal, where to get it, or anything. So because of the flood, the Ice age came, and gradually people re-invented metalworking in time for the tower of Babel.