You would have been just as lost, if not more, in Photoshop (if you had never used it before.) You were doing a simple job that should have been done in a simple program.
I only need to do somewhat basic stuff these days, so photopea.com is more than enough for me. However, now that I look it has tons of new features. Nothing to install, is ad-sponsored by default, and runs entirely client-side.
IIRC, this is a lone developer, who has previously refused what seemed like lucrative catch & kill acquisition offers.
Here is a post with lots of info: