Because you have a BSc, MSc and other professional certificates, you now said, you can't work under someone that have a lesser qualification.

Working under a person that have a lesser qualification doesn't matter and it will be a plus for you because you are gonna gain one or two things from that person.

It will be better to accept the job offer so that, you will be able to gain more experience.

Pls NOTE: Your Certificate without Experience is meaningless to Employers/Recruiters. Graduates are many but majority of them don't have quality Experience and Skills to enable them secure a Job but if you are able to get one, hold it tightly and don't throw it away.

What's your thought about this?