2976 - Jo Nah is born to a poor family on Rimbor.
2989 - 13-year-old Jo Nah becomes the leader of a gang of local hot-rodders.
2990 - 14-year-old Jo Nah's girlfriend An Ryd is killed in a street crime.
2991 - 15-year-old Jo Nah is eaten by an Intergalactic Ultra Energy Beast. He survives by eating it's flesh, adapting to absorb & process Ultra Energy. He becomes Ultra Boy, a local hero on Rimbor.
2993 - 17-year-old Jo Nah joins the Legion of Super-Heroes in it's second recruitment drive. He meets Tinya Wazzo.
2994 - 18-year-old Jo Nah's girlfriend Tinya Wazzo is presumed dead after the battle with the White Triangle Daxamites.
2995 - 19-year-old Jo Nah begins training with new Legion recruit Val Armorr. He discovers that Tinya Wazzo is still alive & unable to take material form.
2997 - 21-year-old Jo Nah goes undercover. To infiltrate a notorious criminal organization 19-year-old Querl Dox uses his access to the Science Police database to implicate Jo Nah in the death of An Ryd. He is arrested and jailed. Only Querl, Rokk Lrinn & Imra Ardeen know the truth.
3000 - 24-year-old Jo Nah is among the member of the Legion of Super-Heroes that are lost in a distant galaxy. He is only kept sane by Imra Ardeen's illusions , causing confusion between them. He returns as Tinya Wazzo is having Brin Londo's child. When the Legion disbands & Tinya's powers fail, he agrees to join Brin in raising their child.
3005 - 29-year-old Jo Nah rejoins the Legion of Super-Heroes with Brin Londo. Querl Dox contacts Tinya Wazzo & restarts her powers, bringing them together again.
The fact that the Legion of Super Heroes was built up during the formative years of the DC universe, and had such a disproportionately high number of characters in it's ranks, means that many of the more obvious, clever superhero names wound up being used by Legion Members. Jo Nah is probably the single best example of this. Ultra Boy. It's such an obvious and yet functional superhero name.
The Legion has a lot of members that are functionally equal to Superboy in power. This creates a bit of a narrative bottleneck that we'd rather avoid, so rather than using all of them (Mon-El, Sun Boy, and so on), we decided to just use this one character. Ultra Boy has a decidedly cool personality, but he also stand out among many of the other Legion members because of his relationships. We're taking cues from a few stories featuring Jo Nah, Phantom Girl and TImberwolf and building something that actually feels really cool. We like how this worked out.