Marwan sits next to 2 phonetic neighbors — Merwan and Marwane are the closest matches by sound. Most share Marwan's Arabic-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"hard stone, small sharp rock"
"lunar, moon-bright"
"devout, pious, ascetic"
"blue"
"blooming, flourishing"
"luxuriant, full of life"
"radiant, luminous"
"judge, magistrate"
"handsome, beautiful"
"devoted one"
"pillar, cornerstone"
"praised one"
"servant of God"
"rich, prosperous (folk interpretation)"
"little rock, harmony"
"grandfather"
"letter Z sound"
"generous, bountiful"
"perfect, complete"
Similar sound: These names share phonetic patterns with Marwan — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Arabic origins, giving them the same cultural heritage as Marwan.
Rhythm: Marwan is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.