In our most recent world, our group pressed to get the 2nd boss The Elder so we'd have keys to get iron. Two ingots of iron (and other materials) gets you the stonecutter, and the stonecutter gets you stone pillars and stone slabs. Wood supported by the stone turns blue as foundation pieces. Once you get two ingots of iron for building supports, you can just coast to get better gear for having more a go at the Iron Age later.