The floodwaters fulfilled their grim purpose, bringing an absolute end to all life on earth. The destruction was sudden and swift. Rather than suffering a prolonged illness, the creatures drowned and suffocated quickly [רד״ק, העמק דבר]. While this specific type of sudden passing is often associated with the peaceful deaths of the righteous, in the context of the flood, it signifies a complete and abrupt halt to all movement of both body and soul [מחוקקי יהודה]. This total eradication was fully completed within the initial forty days of rain [אבן עזרא].
The devastation swept through the animal kingdom, a category encompassing all living creatures [אבן עזרא, מחוקקי יהודה], or perhaps all beings aside from humans [שד״ל]. The primary approach among commentators is that the destruction unfolded chronologically. Birds, being the most fragile, succumbed first to the relentless battering of the rain from above. Next were the domesticated animals and wild beasts. They attempted to seek refuge in mountain caves but inevitably drowned as the waters continued to rise. Creeping and swarming creatures, some of which can survive both in water and on land, managed to endure a bit longer [מלבי״ם, העמק דבר].
Finally, the devastation reached humanity. The sudden conceptual shift from the lowliest creeping creatures to humanity, the distinct and most important of all earthly beings [ביאור יש״ר], powerfully highlights the sheer scale of the disaster [קאסוטו]. Men, women, and children all met the exact same fate [חזקוני]. Humans were the last to perish because they utilized their intelligence and resourcefulness to delay the inevitable. They climbed the highest mountains, built makeshift boats, and desperately clung to trees. Yet, once the water surged fifteen cubits above the mountain peaks, every survival tactic failed, and even the strongest giants drowned [רד״ק, מלבי״ם, צרור המור]. Additionally, the natural human constitution is stronger than that of many animals, allowing people to cling to life longer before finally succumbing [רא״ש].
This total annihilation raises a moral question regarding why humanity faced such a severe punishment before God had given any formal laws or Commandments. The accepted understanding is that they were held accountable for violating basic moral principles that human intellect and common sense alone demand, such as avoiding robbery and murder [חזקוני, פרדס יוסף]. Furthermore, even the otherwise decent individuals of that generation were swept away in the flood because they stood by silently, failing to protest or rebuke the wicked actions of their peers [נחל קדומים].