Congratulations on becoming a new RN! I am both a PCU RN and Nurse Recruiter, so I may be able to provide some insight.
Most hospitals, unless they are very short of RNs, won't start New Grads in the ED. The only exception to that at my hospital (430 beds in the Northwest) are applicants who have worked as CNAs, techs or LPNs in our ED while they were going to school. We hire most New Grads into Med/Surg positions and then they can transfer to a more specialized unit as they gain experience.
Unfortunately, if a manager or recruiter really wants to hire you for a position, reference checks are done within a matter of days and positions are offered as soon as possible. I'm sorry to say that many recruiters don't call the applicants they don't want to hire to let them know. It is very unlikely that you will get a reason, other than lack of experience, to explain their lack of interest. The hiring process is just as litigious these days as patient care and floor nursing, so the less information released, the less likely a lawsuit will be filed.
Best wishes in your job search