What is it like to be “a young overweight-to-obese homosexual and/or gay and/or queer, cisgender male, able-bodied university-and-graduate-school educated, musical theater writing, Disney Ushering, broke-ass middle-class far left-leaning black-identified and classified American descendant of slaves full of self-conscious femme energy and who thinks he’s probably a vers bottom but not totally certain of that obsessing over the latest draft of his self-referential musical “A Strange Loop!” And surrounded by his extremely obnoxious Thoughts?”  Well, you’ll have to get yourself to Playwrights Horizons to see the world premiere of Michael R. Jackson’s brave new musical “A Strange Loop” in order to find out.