Very often people "lack" ideas or motivation only because of this 2 thoughts:
"Ah, this looks too hard for me", or
"Ah, many of those already exists, I want to build something unique". - Every product is unique, no matter if many of the same already exist, it's more about if their product will generate attention or not.
To add on top of your list, people might get ideas by browsing through some API lists as those offer variety of APIs for potential new apps on the market. It can be one API app or mix of 2 or more in something great.
And using (not creating) API usually requires basic research skills and basic programming language skills so most would be fit even for beginners :)
Another way of generating ideas might be just through a name of potential app. By using some name generator like Namify one could generate bunch of possibilities like this

Heh, I could've made a blog post out of this comment :D
Eke Victor Hey. I wrote one a while ago. blog.devmotiv.com/dont-have-application-ideas-few…