Note: The mob can be instinct, alive, or fake. What mob or animal should be in minecraft? Remember: You can feel free to express your opinions! Any answer is great!
The mobs i would like to see are Biome specific mobs like giant scorpions and beetles for deserts, Bears like black bears and Grizzly bears for forests and such. I would also like to see more Nether mobs besides Ghasts and blazes to make it more frightening, such as Lava Monsters, Netherrack plants that try to eat you and Block monsters that hide in walls and surprise attack you. Another thing i would like to see are Ocean mobs besides squids like Fish, Whales, Sharks and such. Not only that, but id like to see a full on Ocean boss thats more powerful than the Elder guardians, It would be called Leviathan. It would take on the form of a giant water dragon mixed with a whale. And would be harder to kill than the ender dragon and the wither combined.
I'd love to see dragons be a thing in Minecraft(Other than the ender dragon, ofcourse). Also, Fortified AI like the new Illagers in their own societies(Like, factioned Kingdoms) would also be a thing. For example, help King A and his rival, King B withh try to coax you, then kill you. You can also wage war with these factions & whatnot.
The Leviathan is a sea monster, much of a snake, or eastern dragon. Other portrayals have described it as a whale.
Mobs should not be instinct. They should be valor. Jokes aside, they don't need to add anymore. The current ones are bad and shouldn't exist (new mobs)
Birds Edit: This isn't a mob but they should allow a way to throw objects to other users. Like throwing an enderpearl but the other user can catch it. idk
Add fish that are visible in the oceans. Sharks included with Dolphins and Whales and etc. Make the oceans a bit more interesting instead of dull and boring
Maybe some different cat breeds. Like there is only 3 at the moment soooo. What about some Long/short haired cats, or some Bengal cats. You know.