Jessen sits next to 4 phonetic neighbors — Jensen, Jesse, and Jenson are the closest matches by sound. Most share Jessen's Scandinavian cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"son of Jesse / son of Jens"
"defender of the mountain"
"a sense of the familiar"
"The love"
"dear friend, huckleberry (with noble prefix)"
"modern invented name; possibly derived from Toronto place name"
"Branch; fern or bracken"
"priceless one, of inestimable worth"
"the metal iron, element of strength and endurance"
Similar sound: These names share phonetic patterns with Jessen — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Scandinavian origins, giving them the same cultural heritage as Jessen.
Rhythm: Jessen is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.