Harlan sits next to 4 phonetic neighbors — Harlen, Harley, and Carlan 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
"rocky land, stony ground"
"young lion"
"divine inspiration, fury, frenzy"
"Paega's settlement"
"growth, abundance"
"true, faithful"
"the bear"
"rock, stone"
"to rule as monarch"
"bald (short for Calvin from Latin Calvinus)"
"emperor, caesar"
"God has given"
"resolute protector's son"
"benevolent warrior"
"supplanter, one who follows"
"of the Cassian family (Roman gens)"
"God is gracious (via John)"
"God is my help, help of God"
"ardor, enthusiasm, fierceness"
"pledge of peace"
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.