How does ovolution lead to both biodiversity and commonalities among
life?

Evolution leads to biodiversity by changing the genetic code of organisms. When evolution leads to biodiversoty its called natural selection. It slowly decreases the popluation of organisms that are less adapted to survive in the world, and increas the population of more strong and adaptable organisms.

For example if there is a pink bird and a white bird, the white bird's population will increase due to its adaptation of camoflauge, and the pink bird will die out because it will be spotted by predators easily. Therefore the species of the white bird will become more common

Explanation:

See pic below

hope it helps u