>>165 opinion: spoilers if you haven't seen these
When Jack tells Ashi about how the universe/stars were formed, they were foreshadowing the entire show & ending:
On XCIII they also used raw foreshadow&metaphor of the white fox being Jack. Thus it can be implied metaphors and foreshadows are legitimate plot devices.
I had this long theory that Jack by himself cannot kill Aku, since they are the same coin, good and evil. However Ashi is from the Dark Side/moon, she can and has killed, unlike Jack. On episode XCVI we are proven just that. While Jack fends off the children, Ashi overcomes herself, kills her torturer and destroy the lab.
In the parable, Moon invited Sun to space, riding the Phoenix (resurrection/conviction renewed) and inspiring the darkness with stars of the hope/arrows they shot. In the same way I see that Ashi will inspire Jack not to go back to the past and restore order, but carry on the future and inspire the next generation to come.
I was highly inspired by https://8ch.net/co/res/837383.html#840123
or oxwugzccvk3dk6tj.onion/co/res/837383.html#840123
Although Jack dying and Ashi continuing his legacy would be a profound ending as well.