It is not foundational, it is one of the many rights that our society recognizes. In Universal Declaration of Human Rights it’s Article 19, coming after 18 other articles. https://www.un.org/en/about-us/universal-declaration-of-huma...

In German constitution it is Article 5 and it is explicitly limited, considering the importance of the balance. https://www.constituteproject.org/constitution/German_Federa...

It is absolutely foundational.

You're talking about laws, but free speech isn't about laws, it's a notion of moral philosophy.

The sense in which it is foundational is as follows: you cannot have democracy without freedom of speech, because without it there is no free formation of opinions. You can't freedom of association or freedom of assembly without freedom of speech. These latter are interconnected, because an aspect of freedom of assembly is to assemble to hold, for example, political meetings.

this is not how the german state (or german democracy?) is built. Freedom of speech has bounds here and this can be defended.