His enslavement by humans is a main event. Then, his escape. Also, his discovery of shamanism.
Thrall's origin starts with his difficult upbringing among humans who had enslaved him. He had a strong will though. He was found by Taretha Foxton who helped him in some ways. Eventually, he escaped and delved into his orc heritage. He discovered his connection to the elements and the shamanistic traditions of his people, which was a key part of his origin and his rise to leadership among the orcs.
One main event in Morro's origin story is his disillusionment with his peers or superiors. He probably felt left out or unappreciated, which made him start to question his place.
In Kenshin's origin story, first, his training as a swordsman in the midst of the political unrest in Japan is a significant part. Then, his actions as the feared assassin Battousai during the Bakumatsu era are crucial events. But most importantly, the moment he decided to turn over a new leaf, to atone for his past by not killing anymore. This decision shaped his future as a rurouni and set him on a path of redemption.
Well, first of all, her joining Overwatch as one of its initial members is a big part of her origin. Then, her presumed death in action was a major event. This led to her being out of the picture for a while. Later, when she came back, it was also a significant event as she had to regain her place and deal with the changes that had occurred in Overwatch during her absence.
The main events include the growth of Overwatch which brought about various ideological differences. Reyes, being in the thick of it, started to question things. And then there was the event that made him feel betrayed, which was a turning point. After that, he gradually became the Reaper, with his new abilities and a thirst for vengeance.
The main event is his birth with the powerful voice. Another is his exposure to the Terrigen Mists. And of course, his training to control his power.
The main event is the fall of the Last City. It was a major catastrophe for the Guardians.
The main event was at a NASCAR race. The crowd chanted something that was misheard as 'Let's Go Brandon' by a reporter.
The main event is the spider bite. It's what starts it all. Then there's the realization of his powers. Another important event is the death of his Uncle Ben which shapes his moral code. And finally, his first attempts at being a hero in his neighborhood.
One main event is her forming the Deadlock Gang. Another is her development of her shooting skills. Also, her early rebellious years against her family's expectations are important.