Modern plastics are made from a wide range of polymers including polyethylene, PVC, and nylon, created from crude oil, natural gas, salt, coal, and in more recent years from bio-matter.
Most plastics are chemically inert and will not react chemically with other substances, making it suitable for storing a wide variety of substances without it dissolving the container itself. But because plastic doesn’t react with most other substances, this means it can take 400-500 years for it to decay.
When plastics were first invented they were marketed as an alternative to ivory and horn, obtained through the slaughter of elephants and other animals. The discovery was considered revolutionary. For the first time, human manufacturing was not constrained by the limits of nature. Humans could create new materials. It was also considered that this development helped not only people but also the environment.