No shit like, her backstory just explains her mindset. You can't judge her if she wasn't raised in a proper household where nobody taught her how to have standards and prioritize herself and her life more. The only people she looked up to and trusted (which also disappeared one by one) is her mother, her step mother, and her sister. Imagine losing the people you love and looked up to, especially that half of your childhood would've been so worse of it weren't for them who taught her morals and surviving the horrible life she didn't choose just so she's safe.
To those who are confused, I agree with the top comment
Why does everyone kept saying that the FL is a doormat? Imagine living in that society where your WHOLE family abuses you mentally? I think some of yall forgot that women back before are almost powerless, especially if they are illegitimate lol. I mean, I will kms immediately if i get to isekaid on this type of novel hahahaha