Sheldon sits next to 3 phonetic neighbors — Shelton, Weldon, and Eldon are the closest matches by sound. Most share Sheldon's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"steep valley settlement"
"settlement near the sword hill"
"variant of Javion (possibly from Xavier — savior)"
"one who shines, illuminates"
"little dark one"
"good race, fine stock"
"little man, warrior"
"son of marsh dwellers"
"calm, tranquility"
"tile-maker, tiler"
"flowing water, river"
"hare meadow"
"Yahweh is kin"
"powerful natural force"
"twin"
"powerful and brave"
"high, exalted"
"modern invented name"
"one who serves"
"kingly, held by the heel (supplanter)"
"one who saves, rescuer"
Similar sound: These names share phonetic patterns with Sheldon — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Sheldon.
Rhythm: Sheldon is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.