Jolly sits next to 5 phonetic neighbors — Polly, Holly, and Molly are the closest matches by sound. Most share Jolly's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"merry, festive, cheerful"
"from the sea, sea fortress"
"of the Verginius family"
"from France, land of the Franks"
"lady, mistress of the house"
"life, vitality"
"mountain, elevated place"
"God is gracious; feminine variant of John"
"star"
"strong wolf, mighty hound"
Similar sound: These names share phonetic patterns with Jolly — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old French origins, giving them the same cultural heritage as Jolly.
Rhythm: Jolly is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.