how did life make a resurgence after the mass extinction of 65 MYA that annihilated the dinosaurs?

I read that science recreated that time on computers. Life along many beach shorelines were sheltered from the destruction. Life in those small areas survived.

Horseshoe crabs, freshwater shrimp, alligators, turtles, crocks, some ferns and at least one palm tree species survived. Interesting all have not changed over millions of years. They look like now, as they looked like then. As You and Me, our ancestors were small mouse-like animals that could hide and live underground. THEY had fur, dino's did not. So when it got dark and cold, lights out for most life, but not all.

the prairies and grasslands, which were once dominated by the dinosaurs were havens for the resurgent mammals after the Cretaceous cataclysm. The mammals of that age were mostly the size of rats. After the death of the dinosaurs, they broke free and began to penetrate every biome on the planet, thus beginning an widespread diverging evolution

The life was always there. But those big ol' nasty dinosaurs kept the tiny weak little mammals under control.

When the dinosaurs died, the mammals took their rightful place in the Food Chain.

Not all life was destroyed at the 65 Million Year ago "Wipe out"

It was just a partal wipe out.