"Many" means "a large number of". It means a larger number than "some", "several" or "a few". For example, if you say:
1. Many people came to his funeral
2. A few people came to his funeral
In 1., you are appreciative of the number of people who showed up, whereas in 2. the number of people is much smaller, and maybe disappointing.
If you say "many people at the party wore a mask", then "many" could mean "more than 50% of the people", hence the sense of "majority". In the biblical reference, less than 50% of the people are chosen, so many could also mean "the majority".