the meaning to be conveyed is the quality of
being able to explore a situation with multiple viewpoints instead of just stuck with one way of exploring the problem
What word (or a few words) will convey this idea?
lateral thinking seems like the most obvious choice to me...
The first word that pops into my head is dynamic. You could describe someone as a dynamic problem-solver, a dynamic thinker, etc.
You might also describe such a person as perspicacious, perceptive or judicious.
A multitasker is someone who can work on many things at once; in some contexts, that may be the word you're looking for.
If you're looking for an idiom to describe this person, you might say she keeps all the balls in the air or fires on all cylinders.
"Broad perspective". Broad being the counterpoint to both "one" and "track" and perspective adding flexibility to the subject of "thinking"
If the subject is a finite automaton, then nondeterministic is the proper word. But when speaking of people, it won't be what you want. For that case, insightful should be mentioned as absent from the wondrous answers given so far.