Sam had seemingly sacrificed himself, it didn't matter if these zombies were evolved or otherwise, they couldn't survive being burnt alive.
There was no way that their bodies would hold up without disintegrating but this also applied to Sam.
However, unlike the zombies, Sam was adept at this and without a second thought, threw himself from the second floor onto the ground.
Sam landed on the ground whilst simultaneously rolling onto the ground to break his fall.
This was why Sam was strong, he knew how to adapt to any situation at the drop of a hat.
The zombies kept pouring into the house because the flames attracted them.
They might have evolved but these couldn't' see, they were your typical runner-type zombie and Sam got rid of them without sustaining a single injury.
That huge chunk of meteorite, Sam wondered how it got there to begin with.