Gordon sits next to 3 phonetic neighbors — Jordan, Cordon, and Gordie are the closest matches by sound. Most share Gordon's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"great fort, spacious hill"
"God has built, Yahweh has built"
"God is gracious"
"God has been gracious"
"dark-skinned, Moorish"
"farmer, earth-worker"
"army ruler, power of the army"
"ash tree"
"cheerful, optimistic"
"sea"
"great river, wide flowing water"
"divine protection"
"of Mars, warlike"
"city of God (alternate interpretation)"
"continuous improvement"
"the island, island dweller"
"peace, gentleness"
"farm steward, granary manager"
"gift of God"
"Gomeric's mountain, power mountain"
Similar sound: These names share phonetic patterns with Gordon — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Scottish Gaelic/Brittonic origins, giving them the same cultural heritage as Gordon.
Rhythm: Gordon is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.