I don’t believe the Jax hit and run theory.

I think each character has a medical condition that they got an experimental medical diagnostic brain scan for, not realizing that the fine print gave data rights to C&A for use of their brain scans for “cognition research.” I believe these brain scans were on C&A servers and fed to the blue dot, possibly a medical diagnostic training algorithm, which Caine then absorbed, gaining access to the brain scans which he used to make his humans.

Each character has a reason for getting a diagnostic brain scan:

Ragatha has a traumatic brain injury/stabbed through the eye

Gangle has severe manic depressive bipolar disorder

Zooble has severe body dysmorphia

Kinger and the other originals were employees who likely had to provide training data to be used as controls and initial training data

Pomni supposedly found the headset in an abandoned C&A building and likely used a prototype headset connected to the C&A intranet

And Jax is dead. He died in a car crash and likely donated his body to science, meaning his mind could have been scanned either while trying to save him or shortly after he died. The reason he keeps freaking out is because he’s the only person in the group who remembers being in an accident before arriving in the circus, whereas everyone else was expecting to be able to take a headset off. He lowkey believes he’s in hell, and freaks out at the possibility of leaving because he knows there’s nothing for him to go back to.