'And We supported him' means we saved him and prevented [and took vengeance] 'from the people' meaning those characterized by strength 'who denied' meaning they brought about the denial of him 'by Our signs' meaning because of his bringing them, and they are of such greatness that it is not hidden.

And when the estimation was: then We destroyed them, He explained it by saying: 'Indeed, they were a people of evil' having no deeds except that which is evil. 'So We drowned them' meaning by Our greatness which came upon them all 'together' even those for whom disbelief severed the ties between Noah, peace be upon him, and them from his family, so they are not counted among his family due to the difference in religious affiliation.