Also, "Hella" seems to me like some regular English word.

It's currently very common slang, but quite recent--I don't think anyone ever said "hella" before max 10 years ago unless they were talking about the Norse death goddess.

I had to do a double take at how hilariously wrong your assertion is. "Hella" has been a regular part of the vernacular in Northern California since the 90's, at least - I should know, I grew up with it. Maybe don't lecture others when you're not well informed yourself?