Classic BASIC does have typing, it just shoves it into the variable name. E.g. X$ is a string, X% is a 16-bit signed integer, and X# is a double-precision floating point number.

This started with $ for strings in Dartmouth BASIC (when it introduced strings; the first edition didn't have them), and then other BASIC implementations gradually added new suffixes. I'm not sure when % and # showed up specifically, but it was already there in Altair BASIC, and thence spread to its descendants, so it was well-established by 1980s.