Kelsey sits next to 4 phonetic neighbors — Chelsea, Lindsey, and Betsey are the closest matches by sound. Most share Kelsey's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"Ceol's island, ship island"
"God is gracious + feminine suffix"
"renowned in battle"
"lily flower"
"peace"
"child of light"
"entire, all-encompassing"
"small, humble"
"fate, predetermined course"
"noble kind, of noble birth"
"princess of the water"
"wonderful, marvelous"
"hollow land, forested land"
"beloved"
"short for Indiana or India"
"settlement on the ledge"
"peace (related to Ériu)"
"woman from Mount Cynthus"
"the burning ones, highest angels"
"a day's travel (original etymology)"
"beautiful, rare and precious"
Similar sound: These names share phonetic patterns with Kelsey — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Kelsey.
Rhythm: Kelsey is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.