Kiffin sits next to 4 phonetic neighbors — Kirsten, Kiffany, and Griffin are the closest matches by sound. Most share Kiffin's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"surname of possible Welsh origin"
"American creative name, possibly variant of Lakia (unknown meaning)"
"bright-headed warrior"
"follower of Dionysus"
"honey bee"
"son/descendant of Aodh (fire)"
"glorious; light"
"God is gracious"
Similar sound: These names share phonetic patterns with Kiffin — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Welsh/English origins, giving them the same cultural heritage as Kiffin.
Rhythm: Kiffin is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.