Jo sits next to 4 phonetic neighbors — Joe, Zo, and Bo are the closest matches by sound. Most share Jo's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"God will add, God will increase"
"lead-colored, blue-gray"
"spear ruler"
"dear little one"
"beautiful, lovely"
"my God is Yahweh"
"sword, firebrand (Germanic etymology)"
"maiden, girl"
"well-born, noble"
"flower garland, grace"
"feminine form of Darian/Darius"
"battle-alert"
"tranquility, cessation of war"
"thunder goddess, feminine form of Tyr"
"resolute protection, helmet of will"
"oak tree, terebinth"
"lake, pool"
"descendant of Raghallaigh"
"set apart, sanctified"
"bright, shining (variant of Helen)"
Similar sound: These names share phonetic patterns with Jo — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Hebrew origins, giving them the same cultural heritage as Jo.
Rhythm: Jo is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.