Complexity around memory management and lifetimes is a definite tradeoff that rust makes. A GC imperative language that uses Sum/Product types seems interesting. I guess that would be swift? I'm not familiar.
Elm if you favor "absolute simplicity", it's a pure functional language which eschews all the advanced type stuff found in most functional language. And I do mean all: elm actually eschews abstract types entirely, it doesn't have traits, interfaces, … except for a limited number of built-ins (comparable, number, appendable, and that's about it, well there's also compappendable which means comparable & appendable, and some people advocate for removing even those: https://discourse.elm-lang.org/t/just-for-fun-what-if-there-...).
It used to have a concept of "extensible records" but I'm not sure even that remains.