That competition for survival and reproduction is the main factor which outweight everything else. Family and social bonds are also among the most powerful forces, but it is the selfish aspect of favoring and protecting one's relatives what matters.
Altruism and kindness are also minor factors, but the weakest ones, and, obviously, cannot be thought as replacement for the general laws of ecosystems based on survival and reproduction, which basically means lifetime ongoing competition for everything that is related to passing of the genes to another generation.
Reframing of evolutionary forces to be more humanistic is, of course, bullshit.
Austruism and kindness might be beneficial at a tribal level as you will likely meet the person again and they or their family may pay back the favour. Even if that isn't a conscious thought by the person being nice.
Nowadays this is less obviously beneficial in our big cities and jet set lifestyles.
And as you said kindness is part of a bigger set of factors and perhaps a lesser one.
