Evolution can be a tough concept to fully grasp. It’s chess, not checkers. There are a lot of moving pieces in the interactions of individuals, species and the environment over time.
There are genes, heredity, sperm competition, mating strategies, predators, microbes, viruses, and climate change. There’s chemistry, biology, physics, quantum effects, mutations, visible and invisible cosmic rays. There is a lot of random chance and a surprising amount of directed development. Evolution is the story of the universe, and it is a big one.
Fortunately, humans have invented animation and have fiendishly clever minds and art skills. The best simple explanation of evolution I have seen is a twelve minute animation from Kurzgesagt – In a Nutshell titled How Evolution works.
It covers almost everything important with wit and style. It highlights the need for diversity at every level of life. It’s an explanation that wasn’t possible until the 21st century.