Your opinions are not facts. They are opinions. Which is why this is a discussion.
6 out of 600 is not an opinion
Them having the least movies out of all genres is not an opinion
600 movies were not for widespread release. It is probably around 200 at best. Even then, outside of your raw data interpretation, the oversaturation involves interpreting the context of cinema.
Let's say that it is 6 out of 200 movies. There are probably 150 or more movies on that list that your average movie-goer has never even heard of. Why? Marketing plays a large role. This is why the perspective is that we are fed a bunch of superhero films, remakes, reboots, and sequels. Quite honestly, if you mashed all those together, they would probably take up a lot of those 200 films than we suspect.
No the perspective that we are fed these movies is simple...people are dumb and also more people rather see the few superhero movies that come out than the dozens of shitty horror, chick flick, romantic comedies, & action movies that come out.