Facile means something that’s easy to understand, or easily accomplished. At one time it could even imply that a person had good manners, or was courteous or affable — in other words someone whose behaviour was easy or effortless.

The word, and its positive senses, came to us through Middle French from the Latin facilis (so the word is closely connected to our facilitate and facility). When applied to things facilis meant they were easy to do, but applied to people it meant courteous or pliant. It first appeared in English in an early printed book, Caxton’s translation of the Fables of Aesop of 1483.

Another possibility could be “effortless.”

Or “snap”. It’s a snap (easy). Then, there’s things that are snappy, quick, etc.

Lastly, “Spartan” can refer to things being simple and not overly showy and yet can refer to someone being fierce and savage.