Reimagining Asylum Processing Act of 2021 This bill modifies the processing of asylum seekers, including by establishing humanitarian processing centers along the southern border. The Department of Homeland Security must establish at least five humanitarian processing centers to process adult asylum seekers who arrive at the southern border and did not arrive as part of a family unit with minor children. The bill imposes certain requirements on these processing centers, including by (1) requiring a rest period of at least 72 hours from the asylum seeker's arrival before an asylum officer may conduct an interview to determine whether there is a credible fear of persecution, (2) limiting an asylum seeker's detention at a processing center to no longer than 15 days, (3) requiring the processing center to provide legal counsel and interpreters, and (4) requiring that appropriate nongovernmental organizations are authorized to monitor the processing centers for human rights abuses. The bill also changes the processing of asylum seekers generally, including by (1) removing provisions requiring the mandatory detention of an asylum seeker after the credible fear interview; (2) prohibiting the use of information obtained from the interview for immigration enforcement; and (3) requiring an asylum officer conducting the interview to consider whether an asylum seeker is eligible for other forms of relief, such as special immigrant juvenile status.