If you want to incorporate an iron age culture or develop an entire iron age setting for your game here are a few nuggets of information to help you develop your world. This isn't a history lesson but some random facts you can use to build NPC's, villages & towns.
During the Iron age the average person had to do multiple jobs, arguably none more important that securing food for the family. Plowing, Planting, Harvesting, Animal Husbandry would have all been common skills. The age of iron token pack has a variety of town and village tokens and vast number are centered on depicting food production for this very reason.
Making charcoal was an essential task as it was needed to produce enough heat to work Iron and Bronze. A charcoal burner would have to spend many days awake balancing on a one legged stool. A smouldering pile of wood packed with clay and earth called an earth clamp would need around 72 hours to create the coveted charcoal.
The common Iron Age building was the archetypal roundhouse. Built using a wooden frame, wattle and daub walls with a thick thatched roof. Wattle is a woven wooden frame and Daub is a mixture of dung, clay, straw and animal hair that is pressed into the wattle. Once dry it forms a remarkably strong wall that is a good insulator. Doorways often faced south towards to capitalise on the natural daylight for as long as possible
Despite being a source of food livestock would often serve an additional purpose to people living in the iron age. Cattle would pull plows, Sheep would provide wool. Fullers would prepare wool by soaking it in water to wash off any dirt before trampling it in a bath of stale urine to prepare and soften the fibers.
Many stone and bronze age monuments and technologies were still used during the iron age. Burial sites were repurposed and used, while the details are often debated there is a vast array of evidence for continuous use and repurposing of burial sites being spanning thousands of years.
While there is some evidence for human sacrifice during this period the idea of burning humans and animals inside giant effigies seems to come from roman writing and should be viewed with a healthy dose of skepticism. Either way it could be an interesting story feature or quest hook to add to your world