Ageing is one of the 'Messemgers of the Gods' that woke the Buddha up to his spiritual journey. The others were Sickness, a Corpse and an ascetic sitting under a tree, suggesting there may be a way out suffering and rebirth.
The Verses describe the sort of wrong understanding that leads to the lower realms and those that lead to happy realms. The Six Realms of Existance can also be takes as human states of mind that each of experinces at one time on another in our lives. But if there is moral justice, thre must be some way that our karma works out towards Nibbana.