There are already some similar suggestions like this:
Vote for more wildlife
Seems like this is a very important topic ;-)
The whole animal wildlife thing needs an upgrade. We need more diverstiy (insects, birds, rats, cats, donkeys, wolfs, ...), more realistic animal behavior (wolf packs, herd animals actually being in a herd), better animal AI.
It would also be nice if animals had more realistic HP values. I had 10 Javelins and thought that would be enough to kill an aurochs bull; it was not... took me 10 Javelins and about 100 hits with my primitive axe to kill it... and while hitting it, it didn't even try to flee, just stood there and grazed -.-
Farming and animal husbandry could be a lot more interesting with more animal wildlife. insect infestations, rats eating away animal fodder, foxes killing chickens in your coop and so on. There could also be stuff like scarecrows, guard dogs, cats to prevent everything i said earlier.
And there could be more specialised storage buildings, e.g. a granary/silo, food cellar. Liquids should not be storable in normal containers but in special containers (bucket, cistern, barrel). And food should spoil over time (specialised buildings preserve food a little longer). Other means of food preservation could also be interesting (smoking, drying, fermenting, etc).