Senna sits next to 4 phonetic neighbors — Sienna, Kenna, and Jenna are the closest matches by sound. Most share Senna's Scandinavian cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"brightness, radiance (Scandinavian)"
"short form of Isabella"
"helper, one who assists"
"torch, light"
"mother, mother of the river"
"to rejoice, joyful"
"flame, light"
"chooser of the slain"
"God is gracious"
"afflicted of God"
"determined protector, will to protect"
"paradise, garden of heaven"
"enjoyment, leisure"
"home power, estate ruler"
"God is my abundance"
"variant of Romy/Rosemary (dew of the sea)"
"flowing water, stream"
Similar sound: These names share phonetic patterns with Senna — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old Norse origins, giving them the same cultural heritage as Senna.
Rhythm: Senna is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.