Code Chicken Lib Do I Need This?

Yes - if another mod relies on it. Code Chicken Lib is a required dependency for several mods - most notably Ender Storage, as well as Chicken Chunks, Translocators, Wireless Redstone and others. Those mods will crash or fail to load without it.

No - on its own. Code Chicken Lib by itself does nothing visible in-game: it adds no mobs, blocks, items, recipes, or world content. There is nothing to "use" directly as a player.

Rule of thumb: if your modpack or a mod lists Code Chicken Lib (CodeChickenLib / CCL) as a requirement, it needs to be present. Otherwise it serves no purpose alone.