Well there are many types of systemic discrimination which contribute to inequality. Racism , sexism, speciesism, ableism, etc.
And of course the resulting issues exacerbate each other when someone is subject to more than one type, so the whole adds up to more than the sum of its parts (intersectionality, as per Kimberlé Crenshaw). I.e. people who are members of multiple social minority groups experience a particular combination of inequalities that members of other groups don't.
E.g. women are treated poorly by HCPs, and black people are also treated poorly by HCPs. Often they have similar issues in these cases, e.g. both groups are patronised, ignored, pain is not taken seriously, conditions are missed or misdiagnosed, inappropriate types or doses of medication are given (there will also be issues the groups don't share). But if you are both black and female, it's likely to be worse in that regard than if you are only one of those things.
It is true we need to address the root causes of discrimination and inequality, rather than just the symptoms of each specific type, if that's what you mean.
But when someone is talking about one type of discrimination they suffer, that doesn't mean you need to try and compete with them by talking about your own suffering in a different area.
So no, female lives don't matter as much in this society. But you don't need to take the terminology used to highlight discrimination against black people to point it out. Unless you are both black and female, for example, in which case it would be appropriate to say "black women's lives matter".
Though it could be argued there aren't many succinct ways of pointing out these issues, so at some point you might have to end up using some of the same words. But there must be some different slogans already used to support feminism.