Need I learn c++?
No! You can use the blueprint-node system.
But it’s a benefit to know about the structure of OOP, without that it’s a little hard to start.
You can create your own game without using C++ directly. But you need understand how c++ coding works. Just watch some short tutorials on youtube.
Yes you can!
I have never used C++ in my life before (I tried CodeBlocks years ago and just ran away back to C#). I am learning with Unreal Engine as I go 
Udemy has a greate series with a few hunded videos.
I suck mountains of meat when it comes to C++. It’s alien language to me. 
I followed blueprints tutorials, once you understand the basics and the logic behind it, you can make a whole game without knowing a single C++ line. In fact, blueprints will end up teaching you C++ without you realizing it.
You can make entire games without touching C++ and do it in Blueprint.
To say that you can make ambitious projects without C++, I would have to say no. You will require C++ at some point.
If you have no background with any programming language (HTTP, Java, C#, etc), you’ll need to learn some basics first to get the most basic out of a game if you’re going to use Blueprint.
You could see Blueprint as a shortcut to learning the basics of programming, but I would recommend to learn C++ along the way.
Use the blueprint-node system.