I say "scalar isn't a data type" because all data is either a scalar or a list of scalars, so a scalar isn't really a type of data, just like dog isn't a type of poodle.
Internally, yes, there are data types representing hashes, arrays, opcodes, etc., but at the Perl language level, arrays, hashes, globs, and scalars are variable types, not data types. And the only thing you can do with those variables is get data from them or put it into them, and that data is always a scalar or list of scalars.
