Jonatan sits next to 3 phonetic neighbors — Jonathan, Nathan, and Yonatan are the closest matches by sound. Most share Jonatan's Spanish-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"God has given"
"God will increase"
"crowned one, garland-wearer"
"nobleman, member of the patrician class"
"sky, shining light"
"god + famous"
"precious green stone"
"wise protector"
"lover of horses"
"gift of God"
"who is like God?"
"supplanter (via Jacob/James)"
"Italian form of Paul"
"man of Rome"
"sacred name"
"Romantically associated with the poet Lord Byron meaning noble and ..."
"the winter season, wet season"
"army friend, honorable companion"
"son of Lars (son of Lawrence)"
Similar sound: These names share phonetic patterns with Jonatan — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Hebrew origins, giving them the same cultural heritage as Jonatan.
Rhythm: Jonatan is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.