I think there are web apps (online) that have templates where you choose your background and title/headlines.

What do you mean? GIMP is simple you find a picture online or make your own and add some text and you're done. Not much simpler than that in my eyes. Just put in a little effort since if you really wanted to do it you could with ease at least I could no problem. So quit whining "I need an apps so I don't have to learn to use basic programs on my system". If your trying to do it on a phone then let apple and google see what you wrote themselves but a PC is smarter if you don't want to end up on a list somewhere.