The NPCs that have their unique walking and standing animations seems to have be...

The NPCs that have their unique walking and standing animations seems to have been replicated too. See here: https://osrs.world/?cx=2956.96&cy=6&cz=3363.12&p=-151&y=2047... . OSRS wiki supports lookup by NPC IDs: https://oldschool.runescape.wiki/w/Special:Lookup?type=npc&i... . So that itself isn't too complicated.

I think the dataset they're using is https://archive.openrs2.org/ . It looks like NPC data might be a part of that. This version has the wrong NPC mappings, and also missing object data: https://osrs.world/?cx=3262.58&cy=8.22&cz=3265.93&p=-244&y=1...

Older Runescape 2 (pre-OSRS) caches have objects but no NPCs.