Is this leading into a 'Have animals souls' debate?
They have btw if there is such a thing as a soul or its consciuos equivalent.
Bit arrogant/convinient to justify the slaughter of animals for food as them being minor living beings,humans were once considered food too by humans.Oh those godly creatures in the image of god....Share your heaven with pigs and cockroaches and moscitos.

Anyway the flood story and the purging of most living things is bs
And did the pie in the sky speak and say everything is food,lets eat god -ah thats done symbolically,catholics have that wafer thingy.
The closest thing to mass extinction is the comet theory.There is no scientific evidence of a mass purge of humanoids.

The question spoke to justification.
Not the reality of the flood.

It is said that men of intelligence can discuss things they do not believe in.

Regards
DL