Harlan sits next to 5 phonetic neighbors — Harley, Harlow, and Harlen are the closest matches by sound. Most share Harlan's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"grey land, rocky ground"
"son of Jens; descendant of John"
"famous joy"
"new, fresh, little new thing"
"Ann's meadow"
"Saxon woman"
"heavenly flower garland, heavenly child"
"little rose"
"bright light"
"little Sarah"
"strong noblewoman"
"hazel tree"
"to measure time (etymological root)"
"land of the Welsh people"
"beautiful, lovely"
"from Devon, the deep places"
"highborn, noble"
"princess, noblewoman"
"creative American coinage blending lyrical sounds"
"noble"
"of noble kind"
Similar sound: These names share phonetic patterns with Harlan — 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 Harlan.
Rhythm: Harlan is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.