Insanity MC Mod will add a large number of new mobs to the game as well as new biomes. In fact, this mod will make the game more varied.
Insanity MC Mod for Minecraft 1.15.2
Incredible mobs like the terrible monster creeper or the Hulk zombie will appear in Minecraft. In addition, dinosaurs will appear from which you can get bones. Everything else you can use to create new items and a portal to another world.