Some are finite, some are renewable. Mushrooms & flax seem to keep growing. Resources gathered from living animals (milking/shearing) will regenerate as long as the animal lives. Everything else is finite. Some resources, like wood, are so plentiful as to be practically infinite.

From what I've seen, there's an absurd amount of ore to boot. Some resources are more limited depending on your actions, to be a bit spoiler sensitive about it. I wouldn't say most resources are renewable, but you can get more than you'd realistically need to complete a run given the right usage. The map randomization is more limited in this one than a decent chunk of the resources.

I'd honestly say unlocking specific recipes can be the trickier part to some margin, just because you can definitely wiff learning them (An increasing chance, but not a guaranteed one) and miss out on being able to create them if they don't drop enough. I have hit a 50% chance to learn before on skirts I think it was and was knee deep in end-game before I managed to actually get it to grant me the recipe.

Luck is what will really crap on your lawn. It's not Level 1 and I used a fountain to find a Level 70 Water Dragon bad (OG Rogue, iirc... Or was it Nethack... It's been a minute...), but it can still get you pretty good (low level necro getting cornered by ranged units with my mindless zombie not really being a great go-getter in the first place...).

Crafting route is definitely an option, but some of the best loot is ripped from the hands of the freshly unliving. :D