What is the sin of someone who was not created in the time of the Prophet, peace and blessings be upon him, and why did Allah create him in this later time and not in the time of the Prophetic mission, knowing that the Companions are better than us?

We are not to object to Allah's decree and wisdom in our not having lived during the time of the Messenger of Allah, peace and blessings be upon him. The Prophet, peace and blessings be upon him, gave glad tidings that those who remain steadfast upon Allah's command at the end of time will have a great reward, as the one who adheres to his religion will have the reward of fifty of the Companions. Likewise, worship during times of tribulation and turmoil is equivalent to Hijra (migration) to him, due to people's heedlessness of it. And we must preserve the religion, enjoin good and forbid evil, and strive in the way of Allah.