Hey there!
Firstly, welcome to Unreal - It’s a fantastic engine and contrary to popular belief, you don’t need to know everything about it to get started.
I second @NEVQ151 's opinion on starting in blueprints. You can build an entire game in blueprints, and I recommend doing just that to get a handle on how Unreal’s architecture works.
In particular, you’ll want to understand how the Gameplay and Gameplay Framework sides of Unreal work.
By Gameplay, I mean the physical objects and tangible game behaviour works in your game - From Actors, Pawns and Characters, to Actor Components, Behaviour Trees, Animation Blueprints, Widgets, Collision System and all of their relevant capabilities.
By Gameplay Framework, I mean the surrounding architecture of Unreal - Most importantly the GameState, GameMode, PlayerState, GameInstance and Project Settings, but also encompassing the lower level architecture of Unreal such as DataAssets, Curves, Timelines, Interfaces, DataTables, Audio & Media.
Creating an entire (small) game will give you a cursory look at each of the areas Unreal needs you to understand in order to effectively design systems to work with it, instead of against it.
Truly, one of the biggest pit falls you will face is taking prior coding knowledge and falsely assuming that it can be directly applied to Unreal. Most of it can, but Unreal is a large codebase, and you should treat it as such. There are utilities, methods & entire helper function libraries that are there to make your job easier and help you.
As you go along, start looking at what the blueprint code you’re writing and using is actually targeting in the c++ codebase, as everything you see in blueprints has underlying code, and a lot of your job as a programmer in Unreal Engine will be writing systems that expose things to blueprints for designers to easily modify.
Finally, get on the Unreal Slackers discord, and have fun!