Slimes can, and awkwardly creepers can too.
no, some mobs can't, such as skeletons, creepers and zombies, but other mobs like spiders or endermen, climb over or just teleport in.
Yup.
Yes. They can climb up everything except ladders or a lip extending off of a wall.
No it can't. A fence 'counts' as being a block and a half high, so players and mobs are unable to jump over it - though a spider can climb it as spiders treat all vertical surfaces as if they were ladders.# Sometimes a cow can glitch out of an enclosure, not much you can do about it.
no,i wish i could climb it like spiderman wahahaha
You can download mobs minecraft comes alive
In Minecraft Classic, mobs can't spawn, so they can't exist naturally. If you play the Survival Test, and when mobs spawn there, you can save it and open it in creative mode so then the mobs can stay there. However, in Minecraft Creative Mode, mobs can spawn, but they can't hurt you because you have no healthbar.
Put it on peaceful
37
As of Minecraft 1.8 (the 2014 "Bountiful Update"), Java Edition had 39 mobs total, cumulative since the game's start.
Mobs are enemies, so I suppose that there wouldn't have been.
No, mobs will not spawn in water or ontop of half slabs.