Su sits next to 3 phonetic neighbors — Sue, Soo, and Zu are the closest matches by sound. Most share Su's Chinese cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"water"
"little rush, little reed (from the leaf shape)"
"noble and pure"
"bright shining one; light"
"cassava meal (as a food-based name)"
"belonging to the ornate Corinthian order"
"Beloved, cherished"
"gentle, charming"
"heart, courageous heart"
"gift of God"
"pleasantness"
"lily (Sue/Susan) + grace (Ann/Anne)"
"wise counsel"
"Dark, little dark one"
Similar sound: These names share phonetic patterns with Su — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Turkish origins, giving them the same cultural heritage as Su.
Rhythm: Su is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.