Likely just overthinking this. I know a lot of stories do this already, and that's why I would assume that not having distinct languages would make the cultures of my world not unique enough to stand out among other fantasy stories.
My story's world has one universal language. My worldbuilding logic is creating a world I would want to live in. Culture and biology will tie the speech patterns of certain races, like those that don't have tongues.
My main fear is that readers will find a single language lazy when, really, I'm going off what I think is an ideal society. There are plans to explore other planets, and I will introduce new languages then.
I haven't developed many ideas for the language yet, but I do have an explanation in the story that connects language to the power system.
I want to know what anyone else thinks about having only one worldwide language, and if it's really considered lazy to do it. Based on what I've learned online, it's seen as generic.