Adam Clarke on Exodus 16:2

The whole congregation - murmured - This is an additional proof of the degraded state of the minds of this people; See Clarke's note on Exo 13:17. And this very circumstance affords a convincing argument that a people so stupidly carnal could not have been induced to leave Egypt had they not been persuaded so to do by the most evident and striking miracles. Human nature can never be reduced to a more abject state in this world than that in which the body is enthralled by political slavery, and the soul debased by the influence of sin. These poor Hebrews were both slaves and sinners, and were therefore capable of the meanest and most disgraceful acts.