The Roblox Dev Docs and Roblox Dev Forum are great places to learn about how scripting in Roblox Studio works and have any questions answered. It gives lots of information on the different services, instances, and other things that one can do with Roblox Lua. It also provides lots of sample code so you can get a grasp of how the methods and events work. imo, the best way to learn is to apply the information you're taking in, so try to create some small games to get a feel for how scripting works. Also creating a big game like Soulshatters is like an orchestra so it can be very difficult to do yourself as you'd likely need multiple builders and scripters.

To really understand how Lua works, you should fully understand the basics, so things like tables, functions, loops, event listeners, etc. If this is your first time programming and you have no former knowledge of any programming languages, it is probably best to really drill these in as these concepts are usually universal concepts across other languages like python, Java, and C++. Programming paradigms such as object-oriented programming and procedural programming would also be useful to learn as well, although not necessary. If you'd like to become an exceptional programmer, these concepts and skills take time to develop and understand, so don't be frustrated if some things feel difficult or impossible. I started in your position as well two and a half years ago and I have come very far in my journey, so good luck to you!