Rashi

'וירד ה לראות AND THE LORD CAME DOWN TO SEE — He really did not need to do this, but Scripture intends to teach the judges that they should not proclaim a defendant guilty before they have seen the case and thoroughly understand the matter in question. This is to be found in Midrash of R. Tanchuma. בני האדם THE CHILDREN OF MAN (ADAM) — But whose children could they have been (except the children of man, i.e. human beings) — perhaps the children of donkeys or camels? But it means the children of Adam Harishon who proved himself ungrateful when he said, (Genesis 3:12) “The woman whom Thou gavest to be with me, [she gave me of the tree etc.]”. These people, also, were ungrateful, rebelling against the One who had showered kindness upon them and had rescued them from the Flood (Genesis Rabbah 38:9).