Kaparot & Pidyon Nefesh

It is necessary to give as much as possible until one corrects their soul. One who cleaves to the attribute of charity finds shelter in the shadow of Hashem, and Hashem acts toward them measure for measure. Just as they performed acts of kindness, so too Hashem bestows upon them unlimited goodness and kindness in the aspect of 'abundant kindness,' and their righteousness endures forever.  
(Pathways to the Soul – Devarim)

The Rambam wrote (Laws of Gifts to the Poor, Chapter 10) about eight levels of charity. Once a person merits to give charity, it should be a complete charity that serves both as charity and as a redemption of the soul. It is good for a person to be meticulous to give in a way where they do not know who they gave to, and the recipient does not know from whom they received (which is the second level as explained by the Rambam there).  
Therefore, this is a merit for the entire Jewish people, even for those Jews who are currently very distant and not so strict about Shabbat, kashrut, holiness, or family purity… but they are full of charity and kindness.  
(Pathways to the Soul  – Behar)

There is nothing that benefits a person on the Day of Judgment more than being a person of charity, especially with those who labor in Torah, with places dedicated to Torah study for its own sake. This is something that rectifies the soul both in breadth and in depth.  
The whole matter of "Kapparot" is in the aspect of a korban (sacrifice). For in the time when the Beit HaMikdash stood, if a person sinned, they would bring a sacrifice and confess upon it, and then they would be forgiven.  
Similarly, we now do this on the eve of Yom Kippur—the "Kapparot" are akin to a korban, and during the Kapparot, we reflect on repentance, which is similar to confession.  
And when a person directs their heart toward Heaven, Hashem rejoices in them.