Jonathon sits next to 4 phonetic neighbors — Jonathan, Nathan, and Nathaniel are the closest matches by sound. Most share Jonathon's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"God has given, gift of God"
"from the town, settlement"
"crown, wreath"
"god of war"
"beloved youngest son"
"God is salvation"
"of God, God's own"
"mountain"
"famous in battle"
"worth, worthiness"
"descendant of Cinneide"
"cloud"
"reminiscent of paladin (heroic knight)"
"diminutive of Isaiah (Yeshaya)"
"belonging to the country, widely known"
"creative elaboration of Finn"
"little bear, bear cub"
"beloved (David) + valley (Devon)"
"place of lime trees"
"a large inland body of water"
Similar sound: These names share phonetic patterns with Jonathon — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Hebrew (Yonatan: YHWH + natan) origins, giving them the same cultural heritage as Jonathon.
Rhythm: Jonathon is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.