Hazrat Aadam (‘alaihis salaam) was sent to the world and commissioned to make it liveable. Thus, the real test for mankind commenced from the time of Nooh (‘alaihis salaam) after everyone was settled. Thereafter, with time deen progressed until the time of Nabi (sallallahu ‘alaihi wasallam) when it reached its peak. Thereafter, with the passage of time the decline in deen began.
When there is a decline, then the good that existed becomes scarce and there is a demand for it. Qualities like honesty and truth are in demand. Hence, the reward for it will be greater. Therefore, this opportunity needs to be exploited to carry out righteous works and deeds that are pleasing to Allah Ta‘ala.