I don’t fully understand the story
what I understand is
Humans created Omnics to help them (Build things or become police)
Some AI started a revolution that gave Omnics their own will and they created Bastions to defeat Humans
but who created the zynyattas and what were their jobs before the revolution?
you mean Zenyatta?
first of all, Zenyatta is one person. Zenyatta is an Omnic who is a Shambali monk
The Shambali were formed after the Omnic Crisis, after experiencing what they referred to as a spiritual awakening. They abandoned their pre-programmed lives to establish a communal monastery deep in the Himalayas. After many years of meditation on the nature of existence, they came to the belief that they were more than artificial intelligences and that, like humans, they possessed the essence of a soul. Recognizing the spiritual equality they held with humans, the monks, led by the enigmatic Omnic known as Tekhartha Mondatta, sought to heal the wounds caused by the Omnic Crisis a generation earlier and bring humans and robots back into societal harmony. Their message was embraced by millions around the world, and they became global celebrities.
if you’re confused about the story you should read the comics, short stories and cinematics. they explain quite a bit. and if you’re still confused you can find pretty much everything on the overwatch wiki.
Do you mean humanoid Omnics in general? They were made for commercial tasks like working at restaurants, advertising, cleaning, etc.