Rowdy sits next to 3 phonetic neighbors — Brody, Cody, and Woody are the closest matches by sound. Most share Rowdy's American English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"boisterous, spirited, lively"
"high guardian, high watchman"
"beloved of God"
"father of peace"
"lives near a bridge"
"well-born, of noble birth"
"open, beginning"
"land where rye is grown"
"from the Denzell estate"
"beam of light"
"God will increase, God will add"
"God supports, Yahweh supports"
"son of the firebrand (short for Tyson)"
"son of the red-haired one"
"one who lives near the fens or marshes"
"from Denmark, a Dane"
"new"
"faithful, loyal, trustworthy"
"God has given"
"army ruler, power of the army"
"bright fame"
Similar sound: These names share phonetic patterns with Rowdy — 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 Rowdy.
Rhythm: Rowdy is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.