Herbert sits next to 3 phonetic neighbors — Hubert, Albert, and Robert are the closest matches by sound. Most share Herbert's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"bright army, famous warrior"
"possibly fire-derived (East Asian linguistic inspiration)"
"son of Diot, follower of Dionysus"
"lord, master"
"destroyer of peace (literal)"
"young warrior"
"three, third-born"
"rock (from city of Tyre)"
"supplanter, one who takes the heel"
"descendant of Caiside"
"son of Hugh, spirit"
"God is my justice"
"keeper of enclosed parkland"
"settlement on a Roman road, farm on the paved way"
"doorkeeper, one who ushers"
"willow farm, ledge estate"
"modern elaboration of Omari"
"of noble birth"
"the hardest gemstone, invincible"
"western meadow, western clearing"
"little fire"
Similar sound: These names share phonetic patterns with Herbert — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic origins, giving them the same cultural heritage as Herbert.
Rhythm: Herbert is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.