Boost 2 main stats, choose any you prefer, no limit for max main stats. If a caveman has reached the max level of 30, 60 main stat points will have been gained, and that is the max amount that can be gained from leveling up rewards.
Get level up points, used to unlock or upgrade abilities from their trees, depending on the caveman's achieved level:
Levels 1-10: 1 point per level
Levels 11-20: 2 points per level
Levels 21-30: 3 points per level
There are 60 total points to be gained, until a caveman reaches the max level (30).
Maxed level cavemen, can still fight for level up points (always get 3 per 1500 XP), until they unlock and upgrade all of their abilities from their tree (see: ability trees), but they will not receive more main stat points.
When reaching specific levels, cavemen get bonuses - chances to draw weapons, items, pets or potions.
Example:
Pool A chances: Common / Uncommon / Rare = 82-15-3%
Pool B chances: Epic / Legendary = 88-12%
Level 1: Get 1x weapon A
Level 5: Get 1x pet A
Level 15: Get 2x items A
......
Level 25: Get 1x item B
Level 30: Get 1x weapon B