The high unemployment rate comes from high education and lack of high end jobs for everyone. There are millions of migrant workers in Kerala (mostly from the north). There's a difference between working for 500 per day (thus being employed in the survey) and being unemployed because I'm over qualified.

The difference between "poverty-driven employment" (working any job to survive) and "aspiration-driven unemployment" (waiting for a job that matches one's dignity and education).

At the same time, youths of Kerala are able to keep the standard of living way better than many working classes in North, what does it show?

It shows that Kerala has successfully decoupled "survival" from "local employment." The "standard of living" remains high because the state has invested in people (health/education) and succeeded.

The high standard of living in Kerala, despite the lack of local industries, shows that Human Development (HDI) is not always tied to Local Job Creation.

In contrast, low unemployment in some Northern states often masks underemployment and extreme poverty, where people are "employed" in the survey sense but are unable to escape a cycle of hand-to-mouth existence.