Some ideas that came out to my mind while playing these last few days.
It would be amazing to have more diversity in enemies. As a garden owner i can totally feel the lack of centipedes, ****roaches, worms and snails. And mantises! Each and everyone with a different material that has to be used to craft their armor sets. If that is not juicy already, imagine what a Lizard could add in terms of gameplay for example. A relentless enemy too big for you to fight and that poses a constant threat to your hard-earned house. Also more interactions with the crow... For example having worms could lead to having a crow's "feeding ground" where you can find more feathers, but where you could also be seen as food by the crow. And what about giving some love to the common fly? In my garden flies are everywhere so having none in game is kind of wrong.
It would also be amazing to have more "building tools". We have, as of now, four different tools (Axes, Hammers, Shovels and Daggers to gather underwater). But building is not just made with that. You could use for example a wheelbarrow (that could require some modifications to the big pebbles you can actually destroy. Instead of giving you multiple pebblets it could give a couple bigger pebblets you can only load on a wheelbarrow). Or for example give multiple uses to the same material (thinking about the berries... so in the end you could make leathers at the working bench, or berry juice if you use them at the smoothie basin, or maybe berry paste if used with a mortar and pestle. There's space for lots of customizations here).
As for mechanics. Some bugs use their exoskeletons to defend themselves better. So hitting for example a scarab with a lvl 1 hammer could either "chip" their armor and drop a scale you have to quickly grab before it turns aggressive on you, or could break their armor completely (more scale drops and armor drops to 0). Again, lots of customizations.
Speaking of customizations. It would be good to have the different needs and survivability-related issues to be defined pre game. For example a bar going from 0 to 5 that defines how many times a day you need to eat/drink. Same goes for sleeping and so on. So at the beginning you can decide to play a game where you feel no survival needs or if you want a hellish gameplay with every need topped up. On the same note, weather has already been said. But that would be just the start... With the rain season comes the danger of floodings making parts of the map more or less dangerous. One thing for sure i am missing is how the weather works on your stats. A sunny day will obviously deplete your water bar quickly while a rainy day would probably keep you moist. And so on.
Ridables is one thing that has been already said, and i second that with few exceptions. Riding an Ant? yes, definitely good as a "working and building ride". Riding a spider? no. Spiders are fierce predators.
That said... thanks to whoever got till the end of this long wall of text. Hope to see a good game get even better!