How can i get the mvnw/mnvw.cmd without maven installed in advance(there doesn't exist any maven on computer at all)?

Question

I know that we can run the command mvn -N io.takari:maven:wrapper to generate the Maven Wrapper files, but what I'm wondering is that

1. what if there's no maven installed in advance, how should we generate the Maven Wrapper files for new or old projects?
2. Should we get the mvnw scripts first and where can we download it?
3. And I also want to know what is the source file in Apache Maven Wrapper 3.2.0 (Source zip) used for?

I want to use the maven wrapper for my projects and I want to rearrange my projects as well as use the maven wrapper to replace all my installed maven.