Simplify the following text for a Grade 16 native English-speaking person.
Original: Over the millennia since , they have performed a wide variety of functions in many different cultures such as : courtiers or equivalent domestics , treble singers , religious specialists , government officials , military commanders , and guardians of women or harem servants .
Simplified: Over the millennia since , eunuchs had a lot of different functions in different cultures such as domestics , treble singers , religious specialists , government officials , military commanders , and guardians of women or harem servants .