Simple isn't the same as easy.
git is simple in the same way Lisp is simple, or Go is simple. git was hacked together in a couple weekends precisely because it's so incredibly simple. There are a few guides where you can write a git in a weekend (e.g. https://wyag.thb.lt/).
Really understanding git is really difficult, though.
A few years after you build a git, you'll get git. I've met only a handful of developers who really grok git, deeply, but it's a journey well worth taking.
The good news is that the surface understanding of git, from having built one, is enough to safely work with the complex commands that trip up most programmers. That's worth a weekend in itself.
I think I was trying to say git is dead simple under the hood, but has lots of useful layers built on top.
One thing beginners trip over a lot I find, is there's lots of ways to do things, and some of those ways overlap, which can be confusing if you don't know what's under the hood.
1. Get a good night's sleep and wake up early, pour yourself a nice cup of coffee or your favorite beverage.
2. Open a copy of ProGit (free here: https://git-scm.com/book/en/v2) and read it cover to cover, while using something like Learn Git Branching (https://learngitbranching.js.org/) to try out what you're learning to get a better understanding.
3. Take a few walks and do your best to read the book cover to cover in a day.
4. Get a good night's sleep to cement the information in.
Git is not simple, but it's very powerful. But I also believe it doesn't take much to become an "expert" (if you already know how to edit text files and know basic command line usage + syntax). I don't think it's a lot to ask to block out a day or two to learn how it really works (at the very least chapter 10 in ProGit, Internals).
I see too many engineers arguing against git from a lack of understanding what commands actually do. Like it or not it's a corner stone of modern software development, and for some good reasons too.