Many questions decided by juries apply a legal standard that inherently mixes questions and fact and law.
For example, in the U.S., about 75% of civil jury trials are in personal injury cases where the operative question is "did the defendant act as a reasonable person under the circumstances?" And, even if you have a 100% perfect account of the facts with completely truthful testimony and authentic audio-video evidence that captures all of the relevant facts, this doesn't answer the question of "what is reasonable?"
Similarly, in fraud cases, one of the questions that a jury answer is "was the plaintiff's reliance upon a misrepresentation reasonable under the circumstances?"
The jury in those civil cases must also quantify the non-economic and/or punitive damages that should be awarded which no finding of fact can tell you.
Issues like reasonableness that require jurors to contribute the context of their life experiences to apply a legal standard apply in criminal cases as well.
Was an attempt to use self-defense reasonably proportionate to the threat?
Was the defendant's conduct criminally negligent?
Was the misrepresentation in a fraud case about something that would be material to a reasonable investor?
Should the words used by an alleged victim in a rape case have been interpreted in the overall context of the communication to have been consent or non-consent if the words were not simply "yes" or "no"? For example, depending upon the context and character of how it is said, the word "please" could mean "yes" or could mean "no".
Was a bodily injury in a case of an assault "serious" or not?
In some cases, these vague legal standards can only be resolved in one way by a reasonable juror and if the jury fails to do so, and convicts someone as a result, the verdict can be reversed by the trial judge after the verdict is entered, or on appeal. But much of the time, a case that goes to trial before a jury will present an edge case where one or more legal standards can be found by a reasonable jury to go either way.
Keep in mind that only 2%-10% of civil and criminal cases started where there is a jury trial demand actually go to trial. The cases that go to trial are disproportionately the edge cases with messy facts that prevent the case from having an easy answer.
The bottom line is that a jury brings the wisdom of the community to the decision-making process to inform vague legal standards in light of their experiences and good judgment. They don't resolve these questions merely based upon the facts presented at trial, but also from the context in which those facts arise that comes from their experiences as ordinary members of the community in which the events took place.