I'm not really sold on the ancestors of villagers being underground in random ice spikes and needing to be thawed out. If you want to do some villager ancestry thing, I feel like it'd make more sense to do that by referencing them instead of having them as mobs stuck in ice. You could have abandoned, ruined structures that resemble the villagers' building style, with archaeological loot that strongly hints to them being villagers or at least related to them.
As for the new items, "but the lore" and "people post the idea a lot" isn't really a good justification for adding these as trades. Let's take copper tools for example.
Firstly, people aren't going to trade stuff for pointless tools. If copper tools were some neat antique you could find in archaeological sites, that'd be better—there wouldn't really be a cost to them, and it'd be clearer that they exist more for lore and less to be useful. However, if you have to trade for a unique item, the player is going to expect the trade to be useful. By the time the player ever finds one of these guys, they're going to be well beyond the point that a copper tool could be helpful.
Secondly, one of the reasons people want copper tools so that copper has more uses. Granted, I don't think this is a very good reason for wanting copper tools—you use very little copper on them, and they'll be replaced by iron in minutes, so it's not like you'll get a lot of use out of all the copper in the world with these tools—but if your argument is going to be "this should be added because people want it", you need to consider why they want it.
Elaborating on the second one, let's take renewable pottery shards. Yes, people would love pottery shards to be renewable, but do you think they want to have to go underground, look blindly for a rare frozen mob, thaw it out, and then come back and trade with it whenever you want to renew pottery shards? Pottery shard renewability should be reasonably accessible, so this isn't a good way of implementing it imo.
When you're adding new items and whatnot, you need to think about their place in the game. What do they do? What are they trying to accomplish? Is it the best way of accomplishing that? A battle hammer seems like it could a really cool melee weapon, but I have no idea what it does that separates it from other melee weapons and makes it worth seeking out.