God is honoured when his children do what he says they should do. Adam and Eve must have told their children how they themselves had disobeyed God and the consequences of their actions. But Cain did not regard the warning.
Abel, however, obeyed God. He gave as God instructed. He gave God his best. He was a hero.
Abel, was loved of God. He was a great example of what it is to be a giver.