You seem to be missing the point.
There's nothing here about שכר.
It's 100% about the reason a נשמה was sent down to this world, 0% about the reward.
Hmm, that is interesting.
My hashkafa was always very different. There is one overall Tachlis Habriya, and that is כּדי להיטב לזולתו, and therefore our mission in life is to merit להתענג על ד׳ which will be לעתיד לבא and we can attain that through all and any of the the תרי״ג mitzvos.
So yeah גמילות חסדים is one of those, however saying that the
reason a person is here is to do someone a טובה just seems inaccurate.
I dont understand this idea of specifying any one over the other, something along the lines of הוי זהיר במצוה קלה...
(This is obviously not taking into consideration each independant persons reason for being here based off his neshama and previous gilgulim, we talking about humanity in general.)