Filtering List By First Letter

I’m having trouble filtering my list. I want to filter it to where it checks the first letter of the word the user inputs and if that first letter is the same as the random letter from the “letters” list. If true, it adds that word the user inputted to the list and if not, it doesn’t add it.

var guessedList = [];
var letters = getColumn('American Sign Language Alphabet', 'Letter');

function randomLetter() {
  let index = 0;
  index = randomNumber(0, letters.length);
  setText('letterOutput', letters[index]);
}

function checkWords(firstUserLetter) {
  var randomLetter = letters[randomNumber(0, letters.Length)];

  // get the user's input
  var wordsMade = getText('wordInput');

  // loop through the letters list
  for (let i = 0; i < letters.Length; i++) {
    // compare the first letter of the user's input with the random letter
    if (wordsMade[0] == randomLetter) {
      // uses appendItem() to add a new item to the word list
      appendItem(guessedList, getText('wordInput'));
      setProperty('wordInput', 'text', '');
      // convert the guessedList array into a string and set it as the value of the wordsOutput element
      setText('wordsOutput', guessedList.join('n'));
      updateScore();
    }
  }
}

I tried everything but I can’t seem to figure out why it’s not filtering it to where it only adds the word to the list if the first letter of it corresponds with the random letter. Its also not adding the users inputs to the list and im not sure why.