Welcome to Atheist Republic Astrid. I hope you find this a place you can enjoy and feel comfortable and not threatened.
I agree, I know many atheists embrace many human (and animal) rights, but I never noticed any strong feminism or men’s rights activist. In fact, when I first encountered “MRA” in this post, I had to Google it to learn what the heck it was.
I try not to make those distinctions, I don’t like grouping people.