What are the difficulties for human beings to settle on the moon?

First of all, human beings should first invent a spaceship that can carry many people together and let human beings immigrate to the moon, just like airplanes now.

Then we have to find a way to make human beings breathe without oxygen.

We should also invent tools that can lead water from the earth to the moon.

Humans should learn to live in an environment with a very large temperature difference!

These difficulties have not been solved, how to immigrate to the moon?