Thanks for following up. I remember seeing the lock and it said you need to eliminate or tame 1 monster before chest can be opened. Not sure what happened then.
I was able to refine my pick and mine some iron and gold. It feels very fun to refine my tools and weapons. Chopping trees down in 2 hacks is so satisfying. From what I read elsewhere, steel isn't in the demo yet. The red mineral in the obsidian which I still can't mine will have to wait... Unless there's some use for iron and gold right now?