Basically everything everyone here is saying is spot on. Great initial hook, but it feels like half of the initial premise is dropped 20 chapters in.
When you have an mc with powers like shapeshifting into other people, you'd typically expect things like fights to be more about decieving your opponents, but that is quickly dropped in favor of the 'I just need to punch harder' flavor of fight.
The MC's awareness and intelligence is also wildly incosistent. In the beginning, the mc felt like he had a lot of awareness of the people around him and picked up on things most mcs wouldn't have. But after the writing falls off, he forgets info mentioned to him 2 chapters ago like the berserkers not being intelligent, etc. Just stuff that makes him seem ignorant.
5/10, read something else, don't waste your time.