Are there any real alternatives to Photoshop?

Yes, I know, GIMP, Corel Draw... no. There aren't any real ones.

I'm looking for some graphics for my little stop-motion animator project. I look specially in sites like DeviantArt. 

You're forced to work with PS because that's what artists work with. That's pretty much the same case with Windows OS. You are forced to work with it because everybody works with it... Right?

But wait. I tried https://www.photopea.com/. It can work with PSDs and does the job for all I want it for.