"If all mankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed ten thousand years ago. If insects were to vanish, the environment would collapse into chaos." — Edward O. Wilson
Both scenarios would cause upheaval, and I'm not sure what he means by a "rich state of equilibrium".
“Rich” refers to the variety and abundance of living things. The total biomass of living things has declined (there’s less overall) and what is left is concentrated into far fewer species than previously.
Just taken as a store of information, the loss is staggering. But from a practical perspective we are less rich; it’s far harder today to catch fish than it used to be, for example.