That's interesting. Main tab has the usual suspects - exposure compensation, contrast, brightness, saturation. Then there are curves, same in every image software under the sun . Then there's shadows/highlights, again - no originality whatsoever. Can you describe what sliders are confusing to you?

Rawtherapee is probably my most used open source app ever, even counting vim. Only issue with it for me is lack of support for Lightroom presets.

For sure the learning curve is steep, but the control you're rewarded with is unparalleled. (Plus there's CIECAM02, one of the greatest color spaces of all time)