Why were there only three vowels in the alphabet?

The presence of only three vowels in the early Latin alphabet—A, E, and I—was primarily due to the limited phonetic needs of the languages spoken by its users at the time. These vowels were sufficient to represent the sounds in Latin and its predecessors. Over time, as languages evolved and the need for more vowel sounds became apparent, additional letters like O and U were incorporated into the alphabet. This adaptation reflects the dynamic nature of language and writing systems.