Luis sits next to 3 phonetic neighbors — Lewis, Louis, and Lucas are the closest matches by sound. Most share Luis's Spanish-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"famous warrior"
"from Laurentum, crowned with laurel"
"industrious, striving"
"God will add, God will increase"
"gift of Yahweh"
"supplanter"
"man from Sebaste"
"God judges"
"from Lucania"
"steadfast, firm"
"strong ruler, powerful leader"
"From the Hebrew 'Yitzhak'; the biblical patriarch Isaac was the son..."
"from Lucania"
"gift of Yahweh"
"the new house"
"From France"
"victory of the people"
"free man"
"free man"
"rich protector"
Similar sound: These names share phonetic patterns with Luis — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic origins, giving them the same cultural heritage as Luis.
Rhythm: Luis is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.