I don't remember what I ate last night
but I can spout off obscure rules to all sorts of game like nobody's business!
Drew the ruined hut card. It says, "Discard this card or build 1 item(knife, rope,shovel or medicine) for free and without an action etc.
I've only discovered a mountain and shore tile so far, so is the knife and shovel my only options? Then the invention goes to the future resources like normal?
You can build any of the 4 items listed, regardless of the prerequisites. You've found an already built item in the hut that you're taking to use for yourself.
The item card goes to the future resources space, and the adventure card goes to the event deck.