Campbell sits next to 4 phonetic neighbors — Camden, Cambel, and Cameron are the closest matches by sound. Most share Campbell's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"crooked mouth, wry-mouthed"
"brave, bold"
"bright-headed"
"little hawk or blackbird"
"cheerful, optimistic"
"vigor and power"
"primordial deity, elder god"
"faithful, devoted"
"the color gray, from the gray lands"
"valley, hollow"
"tournament fighter"
"protector of people"
"high guardian, high watchman"
"alert, watchful"
"son of Nicholas (via Cole)"
"farm settlement of Dudda"
"who is like God"
"dream, aspiration, vision"
"God supports, Yahweh supports"
"conviction, guiding principle"
Similar sound: These names share phonetic patterns with Campbell — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Scottish Gaelic origins, giving them the same cultural heritage as Campbell.
Rhythm: Campbell is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.