BUMS

Currently, the only entrance test accepted by colleges in India, both Government and private AYUSH, for BUMS admission is NEET-UG.

There are institutes such as Jamia Hamdard (Delhi), Aligarh Muslim University (AMU) and state AYUSH colleges that require NEET scores to study BUMS; there is no separate entrance test held by these colleges for BUMS no longer.

College ranking is significant in some ways, especially when ranking the quality of faculty members, infrastructure, amount of clinical exposure, and tied hospitals. Usually, top-tiered colleges will provide solid experiences in hands-on experiences and placements. 
But, for Unani medicine (BUMS), practical training education and accreditation recognition (i.e. NCISM), all matter just as much. I am sure a lower-tiered, yet recognised school, can give a strong BUMS education with facilities.

No, there is no option. NEET-UG is a requirement for entry to recognised BUMS colleges in India. The Ministry of AYUSH makes this qualification within NEET mandatory for all Unani medical admissions.
This will be the case for private colleges too. Without NEET, you may not get a proper admission, as NEET is the only entrance exam for AYUSH courses including BUMS.

The entrance exam for BUMS mainly NEET-UG is conducted only offline (pen-paper based). Students are required to answer multiple-choice questions on a paper-based OMR sheet after which students submit their answer sheet.
While registration and obtainment of admit cards are done online, the actual exam is offline as per the NTA's current policy as communicated to schools. Although students need to insure they keep current by visiting the official NEET -UG site for any changes in either mode or pattern.

Jamia Millia Islamia (JMI) in New Delhi does not offer a Bachelor of Unani Medicine and Surgery (BUMS) program. BUMS courses are typically offered by institutions specializing in Unani medicine, such as Jamia Hamdard University in Delhi.For instance, in 2024, the closing NEET rank for the BUMS course at Jamia Hamdard was 216,398.

For 2024, Lucknow University has released the AYUSH cutoff for BUMS course. As per the Lucknow University AYUSH cutoff 2024, the last round closing cutoff for BUMS stood at 62846, which was more than the previous two years. The 2023 and 2022 cutoff for the same course for the General AI category candidates stood at 54209 and 61703, respectively. To check out the Lucknow University cutoff trends candidates can refer to the table given below:

With a NEET score of 470, securing admission to a Bachelor of Unani Medicine and Surgery (BUMS) programme in a government college is possible, especially under the SC category. For SC candidates, the NEET cutoff typically ranges from 161 to 127, depending on the college and state. Your score of 470 exceeds this range, enhancing your chances of admission. However, cutoffs can vary annually based on factors like the number of applicants and seat availability. It's advisable to participate in the counseling process and explore available options in government colleges offering BUMS programs.?

As you said that you got a seat but didn't join the college, so usually they have strict admission timelines once the counselling and admission process for a particular academic year concludes, it's generally not possible to join later. 

Your were not able to join the college in time so your allotted seat would be cancelled or offered to another candidate.