Pilot agencies work to place experienced people often in short-term contracts in airlines with temporary staffing gaps, much like locum work for doctors. While some agencies also offer long-term contracts with major airlines, these are always for experienced pilots with a proven track record.
These agencies are not like Job Centres. They are commercial contractors who fill places for a fee. Accordingly, they don't take the risk of offering people with no experience to their customer airlines.
Scroggs