Plus the gorilla that is GitHub. Which was significantly better than the contemporary alternatives of SourceForge, BitBucket, or Google Code.

In a parallel universe, had there been a HgHub (with same strong initial iteration as GitHub), I have no doubt that mercurial would have won.

The way I got into git was: I was working on a project using Subversion and wanted to be able to work on train rides (and internet connectivity on trains wasn't a thing back in 2007). Initially I tried SVK, but I found that git-svn actually worked better.

In fact, it worked so well, I stopped using "svn merge" (which took 5+ minutes on our repository for every merge), and started using "git merge" with git-svn instead (which reduced the merge time to <3s, and even the extra git<->svn sync overhead cost only 30s or so). As a bonus, git also reported fewer "merge conflicts" (svn at the time had issues repeatedly merging from a branch to trunk).

So when I ended up picking a DVCS for another project, git was the natural choice since I already knew it. I imagine there are a lot of developers who started out on SVN and took a similar route to learning git, so having a high-quality Subversion bridge turned out to be one of the critical features on the road to adoption. This advantage in adoption then snowballed via forges like GitHub.

(there was a name missing:) and second because Github gave it an interface

This talk by Linus is iconic, if you haven't watched it you should.

https://www.youtube.com/watch?v=4XpnKHJAok8

He talks about what SVN got wrong, specifically, that it made branching easy and it's the merging that's the important piece. Git won because it made merging easy.