Janson sits next to 4 phonetic neighbors — Jason, Hansen, and Jansen are the closest matches by sound. Most share Janson's Scandinavian cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"son of Jan"
"land surrounded by water"
"short form of Cleopatra"
"unique modern American name"
"great chief, mighty lord"
"exalted one (via Aaron)"
"valley dweller"
"God is gracious"
"servant of Saint John"
"son of encouragement"
"rye land, land of rye"
"pastoral paradise dweller"
"the void, primordial emptiness"
"people of the riverside forest"
"army, nobleman"
"from the forest"
"radiant, bright"
"son of Matthew"
"great, kingly"
"the king (colloquial interpretation)"
Similar sound: These names share phonetic patterns with Janson — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Scandinavian/Dutch origins, giving them the same cultural heritage as Janson.
Rhythm: Janson is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.