Kelvin sits next to 3 phonetic neighbors — Kevin, Melvin, and Gavin are the closest matches by sound. Most share Kelvin's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"from the River Kelvin, narrow river"
"defender of men"
"powerful counselor (via Ronald)"
"stammering, lisping"
"ruler of the army (Scandinavian form)"
"gift"
"will, desire, helmet"
"bearer of Christ"
"city of the moon"
"free man"
"young male horse"
"bright, full of sunshine"
"village of the cross, farm by the cross"
"poet, bard"
"man from Hadria"
"broad valley"
"God is gracious"
"gift from God"
"son of the gray-haired one"
"spotted one"
"coal farm"
Similar sound: These names share phonetic patterns with Kelvin — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Brythonic Celtic origins, giving them the same cultural heritage as Kelvin.
Rhythm: Kelvin is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.