Nels sits next to 5 phonetic neighbors — Neil, Niels, and Nels are the closest matches by sound. Most share Nels's Scandinavian cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"champion, cloud"
"deep red, the color red"
"broad valley, wide meadow"
"elder brother, wise child"
"vigor, earnestness, seriousness in battle"
"black banded gemstone"
"from the sky, ethereal"
"small amphibian (secondary association)"
"sea friend"
"belonging to God"
"farmstead dweller"
"beloved"
"light, illumination"
"rye clearing, rye meadow"
"sky-inspired modern name"
"treetop, eloquent speaker"
"sky-inspired modern coinage"
"God will uplift, God will exalt"
"red-haired one"
"from the field, outdoors warrior"
Similar sound: These names share phonetic patterns with Nels — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Irish Gaelic via Scandinavian origins, giving them the same cultural heritage as Nels.
Rhythm: Nels is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.