Probably a bit early for major suggestions but…
Seasons and weather add the effect of non-static world. That is why I love games like BH and sims that have seasons.
Although I haven’t seen much of how ambience will work. seasons/temperature would vary according to location would affect how the “tribe people”? work, and it would affect what plants can grow at a particular time and location.
During autumn, the birch trees would go yellow/red, snowline would drop, plants would go into hibernation.
Winter, snow is everywhere, nothing can grow, no leaves on trees.
Spring, flowers growing everywhere, snowline receding, More plants grow. A lot of rain
Summer, potential for everything to go dry, severe thunderstorms, all the trees have their leaves back
Just a rough outline, honestly ambience already looks incredibly pretty, I would love to see seasons and weather to see a changing landscape.