Kooper sits next to 3 phonetic neighbors — Cooper, Kuper, and Hooper are the closest matches by sound. Most share Kooper's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"barrel maker, cask craftsman"
"born at dawn"
"in him there is strength"
"divine might"
"broad valley"
"west wind"
"cart maker, transporter"
"poet, bard"
"remembered by Yahweh"
"of manly valor, from Andre"
"dove, peaceful one"
"one who lives near the fens or marshes"
"from the Adriatic region"
"army ruler, power of the army"
"gift of God, gift of Yahweh"
"great river, wide flowing water"
"his excellence, his preeminence"
"bold and modern (cultural meaning)"
"pear tree"
"modern invented name, possibly 'sincere air' or 'great river'"
"speckled, freckled"
Similar sound: These names share phonetic patterns with Kooper — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Middle English origins, giving them the same cultural heritage as Kooper.
Rhythm: Kooper is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.