I really feel weird writing this, but being a reader as well as knowing Webnovel readers, it's necessary.
The MC is a girl who was in her early twenties, basically entering the adult world, and ends up in another world with broken vampiric powers. That said, the MC is a teenager who has an arrogant and inconsequential personality and reasoning, because she has OP powers and it's immortal, and since she is immortal, she doesn't need to worry. That's the MC's thinking at first, because she DOESN'T KNOW that actually the world she's in is dangerous for her even if she's immortal.
So yeah, at first the MC will be kind of stupid. But that's what character development is for. When she realizes that her thinking was completely wrong, and that she could get hurt, she will mature little by little.
If you don't like an MC who acts like a idiot at first and doesn't have the patience to wait and see character development, this book might not be for you.
Even so, I invite you to read it, maybe you like it, right?