Let’s take a look at the letter E. In the word ‘shed’, it is the EH, EH vowel. In the word ‘be’, it is the ee, ee vowel. In the word ‘pretty’, it’s the IH vowel, IH, pretty. In the word ‘anthem’, it is the schwa, uh, uh, anthem. In the word ‘sergeant’, it’s the AH vowel. Sah, sergeant. In the word ‘cafe’, it is the AY diphthong. Cafe.
So when you see this letter in a word, you can’t make assumptions about how it is pronounced. Look it up in a dictionary, or have native speaker say the word to you.