They didn't "drown", they "perished"- same difference my friend, they "died". So whats the answer? God declares that none, no not one is worthy of Salvation- (Grace). Since the moment of sin coming into the world, man was unworthy, therefore belonged to satan, because man gave authority over the earth to Satan. This is why God declares Satan is the god of this world and Prince of the air. Until a person so chooses to accept God, during Old test. times, it required animal sacrifices, now since Christ paid the price, its by Grace are ye saved thru faith in the shed Blood of Jesus Christ. Symbolic with animals. After man sinned, sin entered the world by one man, and death by sin. This mean't all living creatures would eventually grow old and die. For animals, this mean't a change for man among other select creatures to be able to eat them. God used the example of the select animals man could and could not eat, to show the difference between God's "Elect" and "Pagans"- (rejected peoples). Why? And "cloven hooved" animals are scavengers, living off the land as it were. Which as stated before, proves why theier bodies contain more parasites found in the natural world than other ones. Later, after christ paid the price for our sins, God now gave Peter a vision of all creatures on a sheet, now being acceptable to eat. Why? To show now, how the Jews were no longer the "only" Elect", but any gentiles who chose to believe in the Gospel too. And the first Gentile converts were lead to Christ by Peter, shortly after seeing that vision, while on that roof where he was staying. so really, in thier "perfected state" all things were originally good. Once in thier sin tainted State, God showed man a greater example of the meaning of His "Gift of Salvation" to His "Elect" thru the animal examples. Even today, man knows that all "cloven hooved" animals are more "unclean" to eat, thus its meat has to be thoroly cooked or we get unwanted parasites from them which enter and live in us otherwise, if not well cooked. This is why God used such animal selections for this comparison. But, back in Noah's Day, man had to learn how to eventually "cook" meat. At first, without knowing better, documented ancient proofs showed, some races ate raw meat, most likely not knowing enough to cook it at first. I pray this helps. God Bless!!