Could the Mars helicopter Ingenuity have been test-flown outdoors at JPL just for the heck of it? (not that they would)
No, Ingenuity was too heavy and underpowered to fly while on Earth.
From 27:30 to 29:00 in the video of a 2021 May 13 press event, one of its designers, Matt Keennon, manually pilots what he called a &quot;terrestrial version of Ingenuity,&quot;  officially named Earth Copter, nicknamed Teri or Terry.  (Reporters have had to guess at the spelling.  The transcript of a 60 minutes segment has Terry, but that neglects I for Ingenuity.)
At 24:45 Matt explains that its only significant hardware differences compared to Ingenuity are that it is lighter (he doesn't say how much), and that its motors are taller, with twice the torque.  Aerovironment hasn't published any hard numbers about Terry, or possibly even any text at all since even its name remains disputed.
But it's clear that they designed Terry to closely mimic how Ingenuity would fly on Mars (see the section &quot;Iterations&quot; in Inside Ingenuity With AeroVironment), so they wouldn't have lightened it and used much more powerful motors for capricious reasons.  It had to actually fly.  A direct quote from Matt at 24:45:

We also reduced the weight of Terry compared to Ingenuity because it's flying in Earth's gravity.

Co-designer Ben Pipenberg also says:

Terry is designed to fly here on Earth, so the motors were redesigned and are more powerful and have a higher torque to handle the denser atmosphere and the higher gravity.