For the paleolithic expansion it would be cool to see world cultures and play as them, such as Aurignacian, Gravettian in Europe even neanderthal cultures. Same with asia and of course play as Denisovans, also the African paleolithic would also be interesting but you get the point by now(lets play as any paleolithic culture in the world.)
One cool aspect would be interbreeding with some of our relatives, for example if i wanted to play as the ancestors of Papuans it would be cool to interbreed with Denisovans with special marriage rituals,
Lastly skin and eye color was different back then, people looked more similar to each other than we do now, so it would be cool to customize skin, eye and hair color as well as hair texture, for example if i wanted to play as western hunter gatherers in Europe it would be possible to play a historic start with blue eyes and brown or black skin with straight hair, or if i wanted more freedom i could customize them however id like