Nils sits next to 4 phonetic neighbors — Niels, Neal, and Neil are the closest matches by sound. Most share Nils's Germanic cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"victory of the people"
"elf friend, magical friend"
"ancestor's relic, descendant"
"swift as a deer"
"elf ruler"
"noble protector"
"Christian, belonging to Christ"
"brave man of power"
"associated, united"
"holly tree"
"glory + power/rule"
Similar sound: These names share phonetic patterns with Nils — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek (Nikolaos) origins, giving them the same cultural heritage as Nils.
Rhythm: Nils is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.