Here 
This forum and https://answers.unrealengine.com/ where a big help.
When you know exactly, which sort of game you want to make and its a 2D 8 bit pixelgame then UE4 is to much perhaps.
Sometimes i think “Hey dumbo, why you not started with a 2D game in UE4”, because some things would be much more easy then?
But everytime i learn a bit more, i am a bit more happy. For me it took around 2 frustrating(!) months to understand the very lowest basics and know some bumps ahead.
I use perhaps 2-4 hours a day of learning and reading. I broke down my project into very small steps, like puzzleparts and someday i will be smart enough to connect them all, in a nice way.
I am old and use it only in my freetime, for a younger one i bet the time is divided by half minimum, like my hairs are!
Every “game” i started, ended in a dead end, because of my limited knowledge and “wrong” thinking of things, how games work.
UE4 is so big and every aspect is fun to understand, but not easy at start.
I feel it’s never easy, because when things go well, i expand and have to master the next bump.
And then bugfixxing in movement controls / axis , when your playerbp is a book full of variables.
Sometimes i have to use my freetime only, to clean stuff out in bp, or make more logical folderstructures…
You talked about leveldesign in 15 minutes, that’s very short time, sounds great. Which style, playable?
Do you like that? https://www.youtube.com/watch?v=XDsJOFyxMnw
It’s all there. Open it, walk around, start klicking on things.
