Oliver sits next to 4 phonetic neighbors — Olivia, Olive, and Olivier are the closest matches by sound. Most share Oliver's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"olive tree, symbol of peace"
"sea and sky"
"full of grace"
"son of Cathal, son of the battle-ruler"
"noble sort"
"lake (from Welsh lynn)"
"to cross over"
"gentle strength"
"noble, noble one"
"God is gracious, Yahweh's grace"
"little Goth, little joy"
"cloth merchant"
"dwelling, place of shelter"
"life"
"quartz crystal"
"harmony, concord, fitting together"
"modern African-American created name combining Sha- prefix with -da..."
"slender young tree, shoot"
"woodland clearing at the brink/edge"
"queen"
"kingly, heroic"
Similar sound: These names share phonetic patterns with Oliver — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Oliver.
Rhythm: Oliver is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.