as for me, these ideas are very good,
but horses need a lot of space, and the island is small, although it's a game, so you can do whatever you want. The spiders won't be added, as the author mentioned, and as for the rats, I find them creepy, and they can also carry diseases, so it's possible that mating with them could be harmful to your body. However, as I mentioned earlier, this is a game, and you can implement whatever you want. After all, there are flies in the game, so I don't have any objections.
Yeah, I'm feeling a bit stuffy.
So, I like your ideas.
sorry for my translation if something is unclear, I'm from Russia and I'm not very good at writing in English.