It's not the lack of conflict, a series can have no conflict and be good. It's the lack of anything unique or remotely original that makes it uninteresting
I think it's fine that it's not original. To be honest, there are very few manga that are original in any way, the vast majority just recycle tropes in different ways. And I find that I don't need originality to enjoy something. It's like eating a burger and fries. I've done it a million times, but I still enjoy it. Not like, every day, but once in a while. And it's the same with seeing the same tropes over and over again. Wouldn't wanna read the same type of story back to back, but once in a while is totally fine.
