I noticed that there is a riding skill in the wiki, but no horses. So I have some ideas about that. What if there were wild horses living in the plain biome, and that they could be tamed with the already existing carrots?

You could build a stable with some shelter and food to keep the animals happy. Shelter and feed could perhaps affect the stamina and health of the horse. Apples would grow well in the meadows, and there could be other foods than just carrots and apples.

In order to ride you'll need to make some kind of saddle etc.
Could require leather and metal to make. Maybe teirs with and without different metals etc.
Saddles could also wear down through use, and mounting could be done by targeting a tame horse with a saddle from the quickslots.

And having mounted combat in the game would be awesome! Even if it would only be practical in certain biomes for terrain reasons.

One more practical use could be packing your mount. If you use some kind of bag on it you could equip it with a "chest" that could follow you around. Maybe by offering it food.