Phineas sits next to 4 phonetic neighbors — Finn, Phinneas, and Fineas are the closest matches by sound. Most share Phineas's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"oracle, mouth of brass"
"fox"
"wide island"
"diminutive of Isaiah (Yeshaya)"
"dear, beloved (associated folk etymology)"
"peaceful ruler"
"crown, wreath"
"shelter, sanctuary"
"modern invented name, valley dweller (from -den suffix)"
"remnants of the lake"
"mountain"
"path to the sea"
"Yahweh is God"
"son of Jack"
"holy river"
"son of the ridge dweller"
"son of Anne, son of Agnes"
"emperor, supreme ruler"
"creative elaboration of Finn"
"old town, settlement"
"myrrh, fragrant oil"
Similar sound: These names share phonetic patterns with Phineas — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Hebrew (Pinchas) origins, giving them the same cultural heritage as Phineas.
Rhythm: Phineas is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.