No it's more like a wide multiaxis field. There are many kinds of intelligence and aspects of those kinds. So many that we might never classify them all.

When we create a mind that is as intelligent as us in the ways that matter for inventing and improving technology, it probably won't be anything like us.

But the mere fact that humans have the levels of intelligence we have proves that those levels of intelligence are possible. We are proof that it is possible for "human level" intelligences to exist.

Now you might postulate that we are the pinnacle and that further gain in intelligence isn't possible, but some people are better at inventing and improving technology (the relevant kind(s) of intelligence) than others. It is at least possible for a machine intelligence to match the greatest human inventors and scientists of all time. But then it could also think faster and with perfect memory and with as many copies of itself collaborating as its hardware can support.

A million Turings, Lovelaces, Einsteins, Newtons, Curies, Da Vincis, Babbages, etc all collaborating, with perfect memories and knowledge of each other's thoughts, operating at 1000 times the speed of human minds. All acting as one.

Is that not a mind more intelligent than any single human mind?

Would that not mean that the previous postulate is incorrect? That we are not the pinnacle?

Now consider that they need only to make one small improvement to themselves and then they are very slightly better at improving themselves.

Could enough small incremental improvements not eventually render them smart enough to start making larger improvements?