The ending was very good and made up for the slowish middle part, although it feel like thats a problem for most episodic released media but especially with web toons. A relatively short read with a satisfying ending is more than you can say for a lot of webtoons.
I thought the twist was going to be that he was homo sapiens and all the tribes he was hanging around were Neanderthals, which is why he was smarter than them (even though Neanderthals would be lighter skinned than homo sapiens at the time the coexisted, but I dont know what the science was on...