How is the poem, ‘Annuals’, a contrast between humans and animals?

Humans can be described as selfish, jealous, restless, unhappy, cribbing, and grumbling creatures. In contrast, animals are peaceful, self-contained, thankful and happy creatures. They do not grumble about their lives, lie awake at night, cry over their sins or discuss their duty towards God as humans do. Also, they do not have a mama for ‘owning things’, nor do they kneel before others. Animals, on the whole, are not unhappy and indeed bring out tokens of man’s good nature lost long ago, when he possessed qualities like love, respect, contentment and happiness.