I think you have not read Descartes' Method. There is much more to it than you say. Virtually no philosophy professor I have met has actually read Descartes. Descartes was NOT a dualist!
He is worth reading.
Here is a deeper dive on his version of science, truth, etc. Much simpler than you think, I think.
He is the father of replication in modern science. He concluded that all you can know is truth is what others have agreed they can observe as truth too.
Otherwise, it's just hallucination. He is also the father of rules of evidence in law. He is the father of modern computational cognitive science...which is a science. The Durants properly give him the title of the father of the Age of Reason, the Enlightenment. Philosophers routinely tear him up with no evidence except his popular writings which you should NOT read.
Here is a youtube.
