Marianna sits next to 5 phonetic neighbors — Mariana, Marianne, and Arianna are the closest matches by sound. Most share Marianna's Italian-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"grace and drop of the sea (Maria + Anna)"
"dark, black"
"close to God, Yahweh has answered"
"strong, vigorous"
"resolute protection, strong-willed guardian"
"crown of laurels"
"dark, rich (possibly referring to the dark Adriatic waters)"
"God is my oath"
"God is gracious, sun (possible alternate)"
"bright, shining one"
"gentle horse"
"water meadow dweller"
"gift, abundance"
"defender of mankind"
"blessed, happy"
"brightness, radiance"
"renowned in battle"
"light, bright one"
"little eagle"
"my God is an oath"
"dark one, descendant of the dark one"
Similar sound: These names share phonetic patterns with Marianna — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin/Hebrew compound origins, giving them the same cultural heritage as Marianna.
Rhythm: Marianna is a 4-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.