RY – From plants we see niflaos haBoreh, all of the amazing and different kinds of living things that give us people life. We can learn a lot from that. From animals, there are other things to learn. I believe it is said that one can learn tznius from a cat (feel free to tell me I’m wrong, just remembering teachings for many years ago). From a dog I recall that we learn chutzpah, as a dog can bite the hand of the one who feeds it.
I also grew up having a dog and loved having one. Nothing like unadulterated love that a dog can give its owner. But dogs cost a fair amount of money and in most frum households there is not so much spare money available to be able to spend it on a dog, who has other issues, like tumah (maybe you have to wash your hands after touching him) and muktzeh, and we have enough human beings to support with our money that having a dog is not really in the budget. From these considerations, there is a complete lack of exposure to these creatures, so the children grow up fearing them.