Lisp was eclipsed by mainstream programming languages in the 1960ords because the machines of the day were very expensive and had limited resources. Thus, the focus was on calculation and efficiency. The limited capacity of the machines meant that programs had to be extremely preprocessed to fit into the computers. Thus, they were precompiled into the machines’ low-level language and only those portions of the program that were necessary were loaded into the computer.
As part of this, the idea of strong typing was considered necessary so that the compiler would generate the appropriate instruction for integer or floating-point addition. I was reminded of this in 1970 when I was looking for a topic for my bachelor’s thesis and I was discouraged from writing a language based on dynamic typing because it couldn’t be efficient for complex structures since it would have to revisit the type information for each element and sub-element again and again.