Like a duck to water, why do we have to help each other? What do you mean?

The story of mutual concern means that two fish help each other and wet each other with their spittle on the dry shore to maintain their lives. Later, he described supporting each other in difficulties. Like a duck to water, it is said that it has got the proper development environment. On the surface, the whole sentence means that since there is a good development environment, there is no need to live a hard life. I don't know what else it means.