a big entry level one would Angela Davis, who is all three. she's also a very influential writer on the left and is taken seriously by pretty much every leftist i personally know (regardless of their ideological lean), so her texts are just generally good from both a "learning" perspective but also "seeing who and what ideas have influenced the contemporary Western left" perspective.

My wife has been reading bell hooks lately.

Do you live in the US? If so, I strongly suggest looking for literature (any literature) by people from the indigenous community who stewarded the land you live on. Even if not strictly "political", it'll give you a wider perspective on the history of your local community. This will be easier in some regions than others, though!

you could get into the works of bell hooks. covering antiracism, anticapitalism and feminism, she is pretty relevant to today's debates.

Emma Goldman is a name that comes to my mind. She writes more about anarchism than socialism though i guess. I'll look through my kindle and see if i have other recommendations

Technically written (or at least influenced) by a women Liberty by John Stuart Mill talks about the importance of freedom, individuality, and a willingness to confront new and old ideas, especially if they challenge your mindset. While it's attributed to John Stuart Mill, John himself is adamant that none of these ideas would've come to fruition without his wife's involvement. He dedicated Liberty to his wife, who passed shortly before it was completed.

John says "Like all that I have written for many years, it belongs as much to her as to me; but the work as it stands has had, in a very insufficient degree, the inestimable advantage of her revision; some of the most important portions having been reserved for a more careful re-examination, which they are now never destined to receive. Were I but capable of interpreting to the world one-half the great thoughts and noble feelings which are buried in her grave, I should be the medium of a greater benefit to it than is ever likely to arise from anything that I can write, unprompted and unassisted by her all but unrivalled wisdom." Historians have tried to downplay his wife's involvement, writing up John's descriptions as biased and blinded by love. But I believe his admiration for her wit was the reason for that love based on how he talks about her. This book was also published in 1859, a period where women were not well represented in literature, a published women was almost unheard of.

There's another book he published later in life that was co written by his daughter called the "The Subjection of Women." I haven't read it myself, but it's a foundational text for feminist ideology. This one was published in 1869 and historians are more willing to contribute some of the work to his daughter. Hope you like them!

'Anyone who is [most humans on earth]' is too big a category for me to make a useful recommendation. Are you reading for a certain purpose? For example, to understand a specific issue, deepen some relationship, help decide on a course of action, or just feel good?