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It occurs to me that it could be as simple as giving them +2 Strength and +1 Wisdom and the exact same features as Lions in 5e.
That means:
Keen Smell. The Leonin has advantage on Wisdom (Perception) checks that rely on smell.
Pack Tactics. The Leonin has advantage on an attack roll against a creature if at least one of the lion's allies is within 5 ft. of the creature and the ally isn't incapacitated.
Pounce. If the Leonin moves at least 20 ft. straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 13 Strength saving throw or be knocked prone. If the target is prone, the Leonin can make one bite attack against it as a bonus action.
Running Leap. With a 10-foot running start, the Leonins can long jump up to 25 ft..
Claws attack and maybe a bite attack.
That would fit both white mana (pack tactic very orderly community based) and lion themes and make them very distinct from Tabaxi. Maybe pounce optional works with weapons.
That would make them Strength based Rangers, good Clerics, Druids, Strength based Monks, Fighters, Strength Rogue, Paladins, and Barbarians.