Not necessarily. Someone who eats dogs doesn't have to "eat everything else." Generalization not applicable.
And that's not the point. Regardless of whether or not plants can be eaten, fish can be eaten, cows can be eaten, etc, they are still held higher in significance than bugs/insects.
That's my point. We treat insects and bugs because, to humanity, they tend to have relatively low significance. And that changes from people to people. Some people love some bugs for their looks. Others do consume them (this practice is called entomophagy). However, the consumption of them is irrelevant to their status of significance (not to mention that entomophagy is mostly taboo or uncommon in most cultures).
For example, the major reason why we kill cows is to eat them. Rarely does one kill a cow, if ever, for no reason. They are killed for food, but also for materials for other things.
However, even though bugs can be eaten, there's not much else you can do with them. And even though they can be a valid food source, people still kill them regardless. It's a natural sense of knowing something isn't very significant. Even in Asia, where, as I said, insects are eaten, they still aren't treated with much care. And for everyone else that doesn't eat them, the life of an insect isn't treated with much respect.
My point is this. No matter how you look at it, bugs and insects are where they are because of significance. We treat things because on their significance to us. That's why we hold the lives of cows, fish, cats, dogs, *insert most of the animal or plant kingdom here*, etc. over than of bugs or insects. We even hold the lives of certain bugs or insects above that of others (read: dragonflies or bumblebees over ants or termites).
Humanity gives significance based on what it does for us. If it doesn't give us something we like (food, material, appealing interest, etc), then we don't respect it very much. Unfortunately for most bugs/insects, that's just how it works.
