I think it may have taken place for a while. Our knowledge of Ancient Egypt shows that meat was a luxury. That means not all of them were always killing animals for food. Things most likely went sour when a non-Egyptian God stepped in and started stealing followers.
Ancient cultures could still live in harmony with other species even though they killed other species for food. It is only modern day societies which take meat/fodder from other life forms for granted and hold them in contempt, be this fauna or flora.
The Australian aboriginal as one example, Respected and valued all other lifeforms, they felt bad that they had to take another life form, and praised (honoured) the spirit of the lifeform which they took, for giving up their life, so that they may survive. The modern day version of this is the prayer before the meal, thank you for the food we eat.
Ancient cultures didn't go on shark hunts or crocodile hunts to the rid the world of these species just because some of their own were taken, they fully understood, they were just as much a part of the cycle of life as any other species and must give up their life to keep that species alive. What goes around, comes around and keeps the cycle of life balanced. Modern mankind is just as likely to go on a witch hunt and kill every one the species for having the audacity to eat a human being, in a, we will teach you who is boss, mentality, or a get them before they get you mentality.