I’d love to see Iron as a resource instead of Gold, and make the trade routes from your base to the neutral market produce the actual gold by selling your resources (Food, Wood, Stone, Iron).
I’d also love to see domesticated animals for all civs, as food production that’s a tier above farming. Maybe food from farms could fatten them.
Some city building elements would also be nice, like very basic production chains. Stronghold had them in the 90s, along with silos and storage platforms, and they were very immersive. It would also be cool to see villagers walking around your town with carts, making it look lived in and allowing more opportunities for villager harassment.