It's all written from a human point of view. Sci-Fi loves to give humananity these 'intangible' advantages over higher-tech alien races that allow us to 'win by dint of what we are, rather than technology'. Ie, we're better. It's rather arrogant.
There have been so many different versions of this over the years, 'why humans are special'. We have 'imagination', we know 'love', we 'build communities' when other races don't
* (which, honestly, is ridiculous looking at how humankind is so damn tribal). Even 'we try harder'. In military fiction, it tends to boil down to 'we have more grit', or 'we are more inspired', or 'we have more ingenuity'.
It really becomes tiresome.
For my money, it's
equally likely humanity's 'edge' over another race would be 'we breed faster'
**. Or 'we're willing to sacrifice our poor as throw-away soldiers in conflicts'. Or 'our leaders don't care who suffers as long as they get their way, and the masses continue to support them.' Or 'thanks to capacity for hatred and tribalism, we do shit to our enemies that other races wouldn't even consider.' Etc.
But no, in fiction it's always some bright, inspirational reason that comes down to 'Cause Humans Are Intrinsically Better™.
I vastly prefer CJ Cherryh's Foreigner series, which has humanity and another race...different, not better.
* Yes, even the otherwise excellent Babylon 5 falls victim to this.
** Anima RPG, I just realized.