Is workjapan website legit for seeking jobs ?

Hello !

I (M21) have for goal in my life to live in Japan and getting naturalized as a Japanese citizen.
And one of the biggest hill on this journey is my future job carrier. So far, I only have my "bac" (my diploma after high-school).

After a conversation with someone working in Japan as a foreigner, it seem that there's two ways to get a visa :
- Having a high level diploma
- Having 10 years of experiences in a job

From our discussion, I learned that casual jobs (convenience store, waiter, receptionist, aso...) are exclusive to Japanese citizens, since it's low effort/qualification jobs.

Yet, when looking online for "job foreigner Japan", I came across workjapan.com that present all those low qualification jobs.

My question is : What did I misunderstood in the work world of Japan, and can I obtain visa via those kind of jobs ?