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"
"wayfarer, traveler"
"son of James"
"ruler of the world"
"seven; divine completion"
"from the rocks"
"strong, virtuous, honorable"
"Lord have mercy (liturgical)"
"modern American creation"
"son of the firebrand (short for Tyson)"
"battle strength"
"may God protect, holder of the heel"
"noble"
"son of Neil, son of the champion"
"ardor, enthusiasm, fierceness"
"estate of the fifth son"
"world-encircling waters"
"great town"
"name of God"
"wise protector"
"descendant of Madan (little dog)"
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.