Vehicles in the eyes of toddlers

A friend's son favorite toys are heavy plants such as bulldozer, huge trucks, and etc. I was wondering why these things attract the boy attention. My own son is also very interested to know about these and different vehicles. At 1+ year, he could identify taxi, bus, van, lorry, concrete mixer, bicycle, etc. I has been wondering why too.

Another related question I have is why characters in children stories are usually animals, and wrongly suggest that they talk like human?

This morning, I thought of a possible reason.

During the ages before machines, or if we were living in the nature, toddlers should be interested to know more about animals and insects around them. Thus, many children books, cartoons and toys are in the form of animals.

In the modern age, living in cities, it is uncommon for them to see many animals except the common ones like chained dogs, sleepy cats, and small birds. Whereas there are many vehicles on the roads, zooming pass, making different sounds, colorful looks, etc.

Thus, I think, vehicles in the eyes of toddlers living in cities are substitutes for animals and insects if they had grown up in the nature.

PS: To me, having grown up in modern city, animals are very complex organic machines.