Looks like the kink and lose fit are due to the wall thickness of that tygon.
It's too soft for tight bends or 1/2 barbs without clamps
Any kinks are perminant damage in thin wall tygon - imho i'd redo that length of tubeing
Tygon is more elastic that pcv tube and you've got the thin wall type
Part number AAC00033 (7/16-5/8)
AAC00034 (7/16-11/16) is the one to get if you want 7/16 without clamps but it's not widely available.
7/16-5/8 in xspc, masterkleer or Primoflex are all fine with 1/2 barbs.
For a first loop buy two metres of masterkleer or coloured XSPC tube.
thin wall tygon is not beginner friendly.