Tricontinental uses the term
Outside the 49 countries of the Global North imperialist camp, making up the vast majority of the world’s population, are 145 countries that constitute the Global South.
The use of the term ‘Global South’ has primarily been a loose, imprecise reference. The actions over the last four years of the now fully aligned and integrated US-led Military Bloc have, however, created a large group of countries that are the ‘Rest of the World’. The ‘Rest of the World’ are thus aligned initially by ‘negative unity’, i.e., all its members are excluded. Consequently, they have become a negation of the imperialist camp. These countries include Russia and Belarus, which are not developing countries but are heavily targeted for regime change and subjugation.
The Global South includes mainly so-called ‘less developed’ or ‘developing’ countries, geographically associated with countries in Latin America, Asia, Africa, and Oceania. It implicitly refers to countries that have been historically marginalised in the global economic system and are all grappling with the legacies of colonialism and imperialism. These countries were often called the Third World
From: https://thetricontinental.org/studies-on-contemporary-dilemmas-4-hyper-imperialism/#toc-section-4-2
It is a term used in anti imperialists circles. But that may be completely missing the point as to whether it is offensive or not and should be replaced. The phrase is definitely clunky, and the above authors admit that too. But they do define it via imperialism so there is a coherent concept lurking behind it.
I'm interested what better word may come about.

I think you are falling into blackpill territory
But I definitely get it. The confusion, odd beliefs, and sometimes just proud anti intellectualism of some folks gets me down too
But like others have said here, more people support socialism and communism than you, I, or even they, know. When doing (what little) outreach I've done, I've been surprised at the amount of support we get. Growing in a very conservative place I assumed everyone was really just as vile as they are. And, while people may be kinda gross at times, more people are on your side than you realize!
If people are anti intellectual when we speak to them, then maybe we aren't using a language that meshes with people. They may feel we aren't speaking with them, just at them. I think there is a strain of anti intellectualism in America, but some of that may be suspicion of "elites" (and coastal ivy league schools are cesspools, but for class reasons) , some of it may be a coping mechanism where people feel like they don't get the terminology (don't talk to people using Marxist lingo from the get go) and feel intimidated or insufficient so they act dismissively to cope.
But I think the working class does want to understand something. But why listen to you VS all the other con artists with a story to sell. People are hungry for some political understanding and a place to belong.
Part of the "problem" here can actually work with us. Many people may not come to a conclusion because they thought about it deeply for years and analyzed all parts. There's too much in life in order to do this for every decision or belief. For some people their politics will follow those of the people they trust. It's a heuristic for cognitive overload.
If we are embedded in communities and workplaces, and are liked and respected people. Real people in others' lives. Then we can get people on our side simply through being trustworthy and likeable people. And we have the extra pro of actually knowing what's up in the world. That is amplified tenfold as revolutionaries become not just individuals but as organized groups and institutions (fingers crossed we get there!)
Some people need to be be convinced through deep argument. Some people are debate perverts. But I don't think most people are. This isn't to imply people are sheep either. It's normal that people will believe what their group believes. So much of knowledge is actually just trust in what others tell you.
I know jack shit about cars, everything I think I know is from what trusted people told me and I simply repeat it. But I could be wrong. That's normal for most things except the handful of topics each of us may have the energy and interest to deeply investigate.
So I think there is hope!
But of course the brainworms are frustrating and sometimes cocerning! That comes with contradictions of our class. You will find people who support you, but also have weird brain worms and horrible beliefs about other things...
That just comes with the territory. You gotta not wait around for the perfect proletariat. And remember the ideas we espouse really aren't as fringe as we may fear. As people engage in this struggle, they will learn. The party, the vanguard, can be like a vessel or school that unites various struggles and unifies them into a revolutionary movement. That means starting with the masses as they are, and finding out how they can move into more and more revolutionary action
But jeez... The brain worms do get me at times lol
But we're historical materialists. The act of struggle, and many Americans will find themselves thrown into struggle as shit breaks down, with an organized vanguard, will help us work through these contradictions. We won't think our way through brainworms or to the revolution. We will act, and it is through that grass touching that the proletariat will, hopefully, consolidate and the brainworms will get worked through.
Then we'll have a higher level of brainworms to work through. Brainworms so far out there that you haven't even dreamt of them. The spiral grows ever higher. Something's coming.