We cannot have words or pronounce words without vowels. Imagine words made up only of consonants. One could not even pronounce a word.
Give examples of simple words made up of three letters : cat, pen, hat, bat , etc., or, words of two letters : at. in. on, etc.
Take out the vowel. How can one pronounce the word ? Vowels act as liants among letters inside words .
"Vowels usually form the peak or nucleus of a syllable, whereas consonants form the onset and coda. ..." [ Wiki dictionary]