Kaysen sits next to 5 phonetic neighbors — Jason, Mason, and Grayson are the closest matches by sound. Most share Kaysen's American English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"modern American creation"
"brave in battle"
"always king"
"God is gracious"
"watchful, vigilant (via Casey influence)"
"befitting a king"
"gentle, loyal one"
"lying flat (large book)"
"without wax (pure, unflawed)"
"carried by God"
"narrow strait"
"dweller by the woods"
"one who cuts cloth, tailor"
"brook, small stream"
"selected, set apart, elected"
"ruler of the world"
"bold warrior"
"great brightness, sea circle"
"brave in battle"
"the herb sage"
"emperor, caesar"
Similar sound: These names share phonetic patterns with Kaysen — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have American English origins, giving them the same cultural heritage as Kaysen.
Rhythm: Kaysen is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.