How should a novice explore into the world of git ?

Depends on the goal. Exploration for exploration sake is probably not going to hold your attention long. git is a tool to track changes. Do you have something you want to change? In other words, you need a reason to use it. Pedantically, your image already has a problem. git is not centralized. It is merely convention that some given local repo is blessed as "upstream". But the whole point is that git is distributed.

Advice: Find a reason to use git. Put your /etc/ under git control, for example. Or something in your home directory (lots of people roll some kind of dotfiles repo). Or contribute to a FOSS project that uses git.

https://learngitbranching.js.org/

Go in a empty directory and type git init .

Then have at it.

Make this your background. Use a gui like gitg if you're learning, but repeat the terms on what each action is doing so you can transition to the konsole

I like to explain it as "advanced undo-redo." Most people who use computers have an intuitive understanding of undo-redo. You can ctrl-z all the way back to when the document was empty, and ctrl-y all the way forward to where you were. The difference with git is that you have to manually create those checkpoints with a commit.

But what if you ctrl-z a few times, and then type something? Most people know that all the changes they just ctrl-z'ed are gone. This is git's first advanced feature: branching. Git allows you to maintain alternate 'timelines' for your file(s), which you can hop between at will. This is also what makes it a powerful collaboration tool: everyone on the team can maintain their own personal branches.

That last capability becomes extremely powerful with the next advanced feature: merging. Git has a number of very nice tools to assist in merging timelines back together, identifying conflicts when needed. This allows teams to set up one "true" branch that is the main (we used to use a different word) timeline. That way, each developer isn't undoing and redoing on the same set of files, they can make their changes in isolation, and when a change is ready, it can be merged back into the main timeline. The proposed changes can be easily seen using git's diff tool, and can be reviewed by the team, further refined, and finally merged with the main timeline. After this operation, the two histories have been joined and everyone else can pull in and start using that change.

I find that's enough to get a new user conceptually oriented. That is, they have a good idea of what they need to do, if not the exact git commands to do it. But that's the easy part, just a quick glance at the man page is all that's needed.

That picture you included is kinda weird and misleading IMO.

First thing: Ignore the "central repository". There is none. git works entirely locally (this confuses the hell out of people who grew up with CVS/SVN, for some reason). You CAN push and pull to other people's computers, if you want, or your own other computer; all Github or whatever is is a "someone else's computer" in the cloud that you can push to. But you also don't need a remote repository at all. Most of ours don't have one.

Seconding https://learngitbranching.js.org/. It's quite nice.

Some stuff you should know:

• A commit is a snapshot of everything in the project (that was added to git at the time).
• A branch is basically just a movable tag pointing to the latest commit, with which you can get to previous commits by walking the chain backwards; when you make a new commit, you move the branch to point to it.
• You can make alternate timelines by going back to a previous commit (without moving your branch pointer), making a new branch pointer (and switching to it), and editing/committing/etc. That's why they're called branches.
• There's an undo history for where your branch has been, git reflog. Can save your butt if a rebase or whatever goes sideways and you get screwed up.
• All your history is in the .git folder in your project folder. Everything. If you back that up you've got the whole history of the project.

-- Frost