Why did unicellular organisms not die out, but survived to this day?

The goal of any species is survival and procreation. Unicellular organisms are no exception. The ability to live for billions of years these microorganisms gave simplicity and adaptability to the environment. Bacteria and microbes survive better than other animal species. If during ice ages, warming, changing living conditions, falling meteorites, most living organisms died, bacteria and microbes felt great. Moreover, almost all microorganisms that are found now were millions of years ago.

One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.