Simplify the following text for a Grade 13 native English-speaking person.
Original: By 2700 BCE the ancient Egyptians had developed a set of some 22 hieroglyphs to represent the individual consonants of their language , plus a 23rd that seems to have represented word-initial or word-final vowels .
Simplified: By 2700 BCE the ancient Egyptians had developed a set of some 22 hieroglyphs to represent the consonants of their language , plus a 23rd that seems to have represented word-initial or word-final vowels .