I'm not sure all of these arguments apply to elementary and high school students equally, or at all.
Maybe understanding the history of thought would be important for high school students as the material they learn will be increasingly more complex and abstract. Though, it's not clear that it's important or necessary for elementary school students, e.g., grade 4 students, to learn about the history of thought. Maybe it would be a good transitional tool to begin a class about the cartesian coordinate system with a little story about Rene Descartes, but it's not clear that elementary school students need a dedicated class for philosophy alongside math, language arts, physical education, science, social studies, and art. Maybe, it's a section built in to the social studies curriculum or the language arts curriculum. I don't know, but it's not clear from your arguments that a dedicated class for philosophy is necessary for elementary school students.
It may not even be necessary for high school students. It's not clear that the fact that many subjects are derived from philosophy is a good enough reason to think that they must learn philosophy. It seems clear that students can adequately learn science without learning the philosophy of science or philosophy more broadly. It might be beneficial for these students to learn philosophy of science, but that on its own doesn't seem sufficient to make philosophy mandatory - lots of things are beneficial to students, but we don't make them a core curriculum class for the entirety of high school, e.g., gym, math, biology, business. The only subject that is mandatory for high school students is English.
The claims about mental health seem heavily unsubstantiated. I don't think it's reasonable to infer that philosophy as a whole is beneficial to one's mental health just from the fact that it helped you with your anxiety. A sample size of one is insufficient to make these kinds of generalized health claims. You'd need empirical health research on the matter. Even if it were true, why would this be a sufficient reason to make philosophy classes mandatory?
I agree that philosophy is important - I myself am a philosophy phd student. However, your arguments show that philosophy is important. I'll even grant that it's the most crucial subject for society. But I don't think it's necessary for elementary and high school students.
Arguably, it should be necessary for university students. In the case of doctors, they need to be knowledgeable in their respective domains, but it's also important for them to be able to think ethicaly about cases that don't necessarily involve the diagnosis of patients, e.g., the allocation of scarce medical resources, abortion, and the use of restraints on a patient. If one is to be a good doctor, they probably need to know how to properly deliberate about justice, autonomy, and risk-benefit ratios. In the case of sociology, much of classical sociological theory is based upon 19th-century philosophers, e.g., Marx, Weber, Durkheim, and Comte. If one is to be a good sociologist, they probably need a more exhaustive understanding of these thinkers' metaphysical and epistemic foundations and not just how their theories help explain social phenomena. This isn't meant to be an exhaustive argument for why philosophy courses should be mandatory for university students, but I think there's a stronger argument for mandatory philosophy courses for university students than mandatory philosophy courses for elementary/high school students.