If we didn't have sun's energy there wouldn't be life on earth.Sunlight is what plants eat. Animals and bugs eat the plants that have sunlight in them. Humans and other animals then eat the bugs and the animals that ate the plants. Indirectly every living thing has sunlight feeding it.
Sunlight provides energy to plants. Then the plants use said energy for photosynthesis to make their energy. Animals eat the plants, and part of the energy goes to the animals. Then, we eat the animals, and the energy goes to us. Basically, we get our energy from indirectly eating plants that the animals we ate, have eaten. Hope this makes sense.
