Evolution did not narrowly require that insects fly or swim, only that they somehow move quick enough to escape predators or catch prey. The open problem of escape led to the narrow answers of water striders tiptoeing on water or grasshoppers springing in leaps. Every worker dabbling in artificial evolution has been struck by the ease with which evolution produces the improbable. The nature of life is to delight in all possible loopholes. It will break any rule it comes up with.
Biological life is a curiosity shop whose shelves never empty.
The catalog of human inventions is far less diverse. Most machines are cut to fit a specific task. They, by our old definition, follow our rules. Adaptation is the act of bending a structure to fit a new hole. If we predefine the organizational structure of a machine, we predefine what problems it can solve.