Jersey is a former cop turned manager of the Gorillaz and there are 2 scenarios I have in mind for for how she ended up with this job
1: She became the manager during phase 3 (Escape to Plastic Beach) after getting kidnapped by Murdoc because he wanted to stay out of too much legal trouble so he decided to get someone who knows stuff about the law to keep things in check (Despite this, he keeps doing illegal stuff)
2: She became the manager at some point after phase 4 (We Are Still Humanz) but before phase 5 (No More Unicorns Anymore) where after seeing an ad saying the band was looking for a manager (This being Russel's idea to help the band keep up with the good press) took the job
Fun fact, the little hairclip Jersey has on is a reference to Cyborg Noodle
