The 737 fleet is expanding. The 757 fleet is shrinking. There are more than enough F/O's within the company for the 75/76 left hand seats.
If you were misled thats a shame. But the website does say...
Pilots joining our 737 fleet may have the opportunity to transfer to our 757/76 fleets after a 3-year period subject to vacancies
If anyone gets a direct entry Captain job on the 757/767 there will be a few eye brows raised.
MAX