Leftist theory tends to be information heavy, dry, and dense. My way in was through books that were transcriptions of Noam Chomsky's radio appearances, compiled into a book called How The World Works. He speaks with clarity, but is also casual, and respectful enough to convince liberals without them even realising it. That's exactly the position he's held for most of his career, and I think that's a valuable thing that shouldn't be overlooked.
I guess he doesn't write much about Socialism explicitly, but he does just about draw the battle lines, and reveal capitalism's ugly side.
I know this site doesn't like Chomsky too much. I can see his shortcomings. He is a liberal these days. He's had bad takes in the past. But he's not poisonous, and he is true baby leftist level. I would say Michael Parenti book are better for post baby level leftists. He's a very rhetorical guy, and I think he speaks to post baby leftists because he puts what we've learnt already in such an emphatic way. I think he puts some libs off, because he's such a powerful speaker. He lets his anger show. He's right, for sure, but I think he's not for true babies.
Still, his speeches do make for great listening for something that's information rich but also funny. Maybe it could appeal to certain baby leftists, so long as they're not too civility fetishising.