1. How is it 'intelligent' to believe 'humans' exist for purpose beyond 'self'?
I know of No lifeform that is not 'self-serving'.
If one is not sacrificing for someone else how do you tell if it is true love. Justice requires true love to have some sort of sacrifice attached to it. God the Creator gave us that example when He died for us even when He knew we were to capable of sacrificing for Him in the same way He did for us.
What is 'Good'?
What is 'Evil'?
We were created in the Image of God to live for the same purpose that He lives which is to create and and using that creation to help others by improving their lives which glorifying them and by which we exemplify God which glorifies Him.
Parents working hard to raise children and passing the joyful experience of being sacrificial to them so they can do it for their children.