Is it normal that i have a habit of calling people i'm angry at " subhumans "?

Yeah, I've done that too when someone's actions were the sort of actions one would describe as less than human-like.

I dont insult their humanity I just insult their inteligence.

That's a pretty good insult. I like "Mongoloid."

Subhuman specifically isn't one I'd go for, but yeah. So long as you don't literally believe they're subhuman this is pretty standard behavior imo. I do the same, except my preferred word is "humunculus"

You’d be a “subterranean” if you said that to me while I was in a mood.

I kinda do that too, although I prefer the term "troglodyte" personally.