Reimagining the Shadow Isles' Champions: Who were they?

Not much is known about the Shadow Isles but it is clear most of its champions are undead or were reborn somehow into another being.

With this in mind, what kind of past did they have before they died. I had this thought last week and started to wonder myself. Not to start a conversation similar to Zed = Nocturne but there haven't been any known centaurs introduced in lore. My suspicion is that Hecarim was once a cavalryman with a noble steed that somehow died and combined with his horse. I also noticed that Hecarim had a lot of crescent shapes on his armor and thought that it would be easy to mess around and Lunari up his armor.

I imagined Hecarim was never named Hecarim. He had some regular name similar to Leona or Diana. Before death he must have been a member of the Lunari and therefore an ancestor to Diana and Leona. He must have been a fearsome warrior that wielded a long spear and led a band of other horse-riding knights. How he ended up dead I imagine was through the glory of battle. Perhaps something from the Shadow Isles slew him. I was thinking that perhaps he was sliced in half along with his horse and through a cruel twist of fate he was melded to his steed in death. As he woke up his memories were tainted by a screaming wrath that overtook his mind. Over the years his memory decays and he then transitions fully into the being known as Hecarim. Anybody else have crazy ideas?

Also picture started off with a light trace. I'm terrible at detailing so I just kind of went over it all quick lol. The armor took a while to imagine into a Lunari theme but I looked at Diana's splash art for a while.