Git

Git is probably the best version control system (VCS) there is.
It's easy and can be lightweight, but also has tons of possibilities for using graphical (/web) user interfaces.

Client

The Client is pretty simple to understand.
With only a handfull of commands you should be able to get your versioning going.
For servers with web interfaces there are different cli tools to control it
without using a browser.

• Arch based systems: pacman -S git

There is also an interactive fixup guide by Seth Robertson.

Server with web interface

Web interfaces for git are quite useful for easily showing code to other people.
Additionally it is easy to collaborate together.

• Gitea is an open-source and selfhosted and can be dockerized.
• Github is the go to system for many people. Not
  selfhosted, owned by microsoft (cli-tool).

Server without graphical interface

If you don't need a bloated web-interface a more basic approach is more than enough.

• git-server-docker is a pretty
  basic docker-container for git.