Life without lighting would not make sense at all. It would be impossible to imagine life without lights. In animation, lights are what brings things to life to a character or a room or an object. Lighting is essential in animation because it really helps make a scene real, it helps create real characters and gives something life from something static. Lighting is one of the key aspects of animation, it plays a vital role in defining how a scene will look. It helps create depth and complexity and the overall mood of the scene.
Within 3D lighting there are 2 main purposes. First is lights produce shadows which help ground the 3D models and make them appear clear; the second is it helps add depth and complexity to the models through use of several techniques such as shading and texturing.
In 3D animation a scene cannot work without any lights. When a scene is rendered, the whole appearance of the scene can only be visible through lighting. The textures and models need lights or they will appear dark in the scene. Therefore lighting can make or break a scene. Lighting can be a difficult aspect to deal with as it can cause unwanted scenes - a scene being too bright or too dull. Thus it is up to the animator to work and experiment and research with the lighting. The same scene can look very different with different or even the same lighting, therefore lots of experimenting helps to understand what works and what does not work.
Effective lighting can help a scene tremendously. It can create the mood and atmosphere of a scene. The use of colour plays a critical part for setting the tone of the scene. Colours evoke different moods. Colours like red can create warm or happy scenes while green or blue can create some calm scenes. Shadows also help to enhance the mood of the scene. Crisp shadows can be created by hard, distant lights - it helps set the mood of really hot environments or dark, mysterious scenes. Therefore lighting has multiple approaches to it and requires experimenting. Here is an interesting page that may help with lighting: http://www.3dartistonline.com/news/2015/04/24-things-you-need-to-know-about-lighting/