Poisonous snakes make perfect sense without an omni-benevolent god in the picture. The questions only arise when such a creator is assumed to exist.
Any Jdub can tell you that before the flood all animals fed from plants only. Evolution took place after the flood.
As you can tell from Genesis, Chapter two, man was created before all plants and animals. You will soon see evidence of man existing before other forms of life. The reason J was looking for a mate for Adam among the animals was because he liked diversity, and wanted to see if man would pick a mate from one of the snakes (who at the time could talk and walk erect). The snake became upset because she really liked Adam and become jealous of Eve. She overheard J saying that her head would be crushed, and evolved poisonous fangs as a preventive measure. Man's sin caused illnesses, virus, accidents, etc. after sin was committed. All kind of deadly microbes started sprouting after they ate the forbidden fruit. J wanted to prevent more deaths because man's sin started to crack the firmament (firm, or solid plane) that held the top layer of water above the sun, the moon and the stars. He tried to prevent the water from killing all the animals so he had Noah construct an ark and feed all the millions of species, pack them in a single day, and this is how Earth was saved.
I can also get some Acapulco Gold.
Jehovah is not omni-benevolent god. Who told you this? Would an omni-benevolent god do the destruction J has done?