MC (Tsukuru) and 107 other classmates got summoned to another world to be heroes to kill the demon lord. MC had a garbage skill (cooking) and was abandoned in a forest where he was expected to die.
But it turns out that:
There doesn't seem to be a demon lord
The humans are trying to repeatedly do this summoning
The goddess of Japan is pissed that this other world had the guts to steal so many of her citizens (and doing it in a way that threatened to explode all of Japan / Earth if she blocked it), so she made sure the MC gets cheat-level powers to be able to take revenge and prevent them from ever doing it again.
Massive luck, more powerful versions of his cooking skills, and the ability to gain abilities from the food he makes.
Every race has a leader (an "Ancient-Type") that is quite powerful. They always have two lives, and if they die for good, then another member of that race will become an Ancient-Type and gain the memories of the previous one.
The humans' Ancient-Type is Temas, the old guy that they're tormenting in this chapter. He's already had one of his lives taken by the MC.
It hasn't been fully explained why, but Temas is the one that has been doing all of these summonings in order to try to get a powerful hero with light-magic to do something...
The current revenge is for MC to use his powers to replace all of Temas's allies with doppelgangers and have them all rebel against Temas's country "Rade".