My supporting POV on selfishness motivating human moral values

[smax]

I think self-interest may be a better term for what the OP describes, anyway.  Selfishness implies individualistic greed.  Self-interest is different.  It is in my self-interest to live in a thriving community and to do my part to help make it that way.  And that means doing my part to fit in, partake in and/or offer services, etc.

I'd agree that people would probably more comfortable with the term self interest, and I certainly have no objection to that term being used in it's place. They are basically one and the same. 

But, even then, self-interest doesn't drive every action.  Empathy is a big player as well.  It's what drives charity, and is a huge component in interpersonal relationships.  Sure, there may be some long term benefit towards helping someone, but most people don't think like that.  They simply see someone in need and work to help them, regardless if it's financial help, physical work, a shoulder to cry on, or simply being there to listen.

How many people do you think are charitable and like to help people and yet do not have any expectation of, in the very least feeling better about themselves as a result? And, for many others, there are even more significant motivations at work, like personal recognition or having someone feel like they owe them an unspoken debt of some kind. 

When you say most people "don't think like that", surely you know that is a very naive generalization, right? Do you really believe that people, in general, operate without an agenda of some kind or at least on some small level?