I't my Opinion YMMV

 What is the purpose of a Photographic Challenge?

Is it ok to recycle photos you have taken in the past to fit the current Challenge?

If so what did you learn? If the setting that were used on you previous camera do they fit your current gear? Ok you met the "challenge" but did you actually learn anything new or find a new location.

In my OPINION it was a useless endeavor. You only searched your catalog of photos to fit the goal. Even if it's the same old subject, challenge, find something new. Get out of your comfort zone. Take a photo. Use your camera not your computer.

That my Opinion. 

I'm new to (fill in the blank) I just ...

It's not mine to reason ...

(Ours not to reason why, ours but to do and die.

Alfred Lord Tennyson)

But why we, well some, get some shiny item then purchase accessories that they don't know to use or fit.

For example, "Hi, I’m fairly new to photography and have an Olympus E-M10 Mark II camera, I just purchased a secondhand lens ..." That doesn't work likely the wrong mount.

The message is understand your equipment before you accessory. For cameras learn its capabilities and photography. Better photos is not paved by gear. Learn the craft then you will learn the gear you can actually use or need.