Charles sits next to 3 phonetic neighbors — Charlie, Charley, and Carl are the closest matches by sound. Most share Charles's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"free man"
"divine"
"stone"
"God will increase, God will add"
"from the brook"
"earth (in Arabic, adama)"
"universal, whole"
"twin, double"
"barrel maker"
"cloth walker; fuller of cloth"
"the Lord is my God"
"God is gracious"
"determined helmet-wearer, warrior protector"
"God will uplift"
"From the Scottish place name Logan; a topographic name from Gaelic ..."
"riverbank, shore"
"gift of Yahweh"
"rival, eager to excel"
"man from Laurentum"
"Yahweh is God"
Similar sound: These names share phonetic patterns with Charles — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic origins, giving them the same cultural heritage as Charles.
Rhythm: Charles is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.