Plants are important for many reasons. One is that plants produce oxygen, which we need to breath. Also, plants are food for humans and animals. Without plants, much of the life on earth would quickly go extinct.

Most living things depend on plants to survive, including humans. You can see this by looking at a food chain, which connects living things to their food sources. Animals survive by eating plants or other animals. If you keep following the line of animal food sources, you will eventually reach the herbivores, animals that only eats plants.

If there were no plants, herbivores would die out. Then there wouldn't be enough food for the remaining animals to survive, and all life would die out.