That's a good question -- probably there is no big deal about this -- in hind-sight. However, in the beginning, it was a big deal because the idea used to be that natural selection would choose
individuals who would be more likely to produce
their own offspring. So why is it that some individuals will seem the "share" resources and danger? Why do some individuals even behave in ways that will increase the likelihood of their own deaths (by giving audible warnings that an approaching predator is sure to hear) for the sake of the tribe? In fact, creationists will scream what a "big deal" this all is, and how it can't be explained by evolution.
You are correct. Like so many intriguing mysteries that start out as a "big deal", once the problem is understood and solved, its resolution shows that it really is a rather mundane phenomenon.
"Intellectually, scientifically, even artistically, fundamentalism -- biblical literalism -- is a road to nowhere, because it insists on fidelity to revealed truths that are not true." -- Katha Pollitt