I think it will throw an error if you declared my @array

> Why can't we just `@array[1]`?

Because that could return an array or a hash if you are dealing with structures likes arrays-of-arrays (AoA) or arrays-of-hashes (AoH).

To my naive take, it makes much more sense to only identify high level objects to put them under one category (arrays, AoA, AoH -> @) then consider everything else as "uncertain" and default to $.

Otherwise, you would have to declare AoA and AoH differently (ex: my @@AoA; my @%AoH;) and then the interpreter could see @AoA[1] and %AoH[1] as valid but %AoA[1] and @AoH[1] as invalid.

I could see that as potentially having value to know at a glance what you are dealing with, but it might break many things, and casting to a new object with my %aoh_1 = %{ $AoH[1] } makes more sense.