As a slight refinement of your point, C does have storage map based N-D arrays/tensors like Fortran, just with the old column-major/row-major difference and a clunky "multiple [][]" syntax. There was just a restriction early on to need compile-time known dimensions to the arrays (up to the final dimension, anyway) because it was a somewhat half-done/half-supported thing - and because that also fit the linear data model well. So, it is also common to see char *argv[] like arrays of pointers or in numerics sometimes libraries which do their own storage map equations from passed dimensions.

Also, the linear memory model itself is not really only because of Algol/Turing machines/theoretical CS/"early" hardware and mechanical sympathy. DRAM has rows & columns internally, but byte addressability leads to hiding that from HW client systems (unless someone is doing a rowhammer attack or something). More random access than tape rewind/fast forward is indeed a huge deal, but I think the actual popularity of linearity just comes from its simplicity as an interface more than anything else. E.g.s, segmented x86 memory with near/far pointers was considered ugly relative to a big 32-bit address space and disk files and other allocation arenas have internally a large linear address/seek spaces. People just want to defer using >1 number until they really need to. People learn univariate-X before they learn multivariate-X where X could be calculus, statistics, etc., etc.