They did in C, from one of the language authors even, and it was not accepted.

https://www.nokia.com/bell-labs/about/dennis-m-ritchie/varar...

By the way, both Extended Pascal, Mesa/Cedar and Modula-2 have them, under the name of open arrays.

Basically it took Go, C# and others for C++ to finally get its span.

C probably never will.

Everybody knows that C++ did not invent the concept of spans and that it was late to the party. It doesn’t change the fact that (presumably) nobody made a proposal to the C++ standard.