2 Book(s) Related to wasteland

Clad in gray mist, kneeling on iron rocks, working as a menial laborer, everyone thought he was just a worthless nobody, groveling in the dust for an old pocket watch. His
in-laws found him filthy, his fiancée defected to a new master, and Lord Calder treated his obsession like a leash, subjecting him to arbitrary humiliation and summons at will.
Until that day, Calder shattered his last hope with an arrow, throwing him into the horde of zombies as a human sacrifice. Everyone thought he was doomed, but no one suspected—
the man kneeling in the mud wiping his boots was actually the reclusive lord of the strongest city-state in this wasteland, possessing S-class superpowers and ultimate weaponry.
He endured, solely for the truth and reckoning.
When he returned from the horde of zombies, radiating overwhelming power, the once high and mighty man knelt outside the city gates, weeping and begging him to open a path to survival.

On my first day as an intern at the zoo, the old director assigned us animals to care for.
In my previous life, my classmate Jack chose the easy-to-care-for African elephant, while I was forced to take on the brutal Siberian tiger.
A month later, the apocalypse struck, and the Siberian tiger successfully evolved, leading me to escape the encirclement.
Jack's elephant, however, couldn't outrun the mutated species and was torn to pieces. Driven
by jealousy, the surviving Jack incited a mob to brutally beat me and the giant tiger to death, dismembering and cannibalizing us.
When I opened my eyes again, I was back on the day the animals were assigned.
Jack had already taken the Siberian tiger, pushing the elephant to me, and I knew he had also been reborn.
But what he didn't know was that the Siberian tiger he had devoured was also reborn with me.