Unity is a way to get in quickly with a game engine. It does a lot for you in terms of collisions, rendering, editor tools, and gives you multiplatform out of the box. If you're interested in just making a game I would say grab that or another game engine such as Game Maker Studio 2 or Unreal. If you want to better understand how games work under the hood you could look into some books that have you make a 2D engine yourself in javascript or other language. Another way to go is to use a framework like Love2D or FNA that give you a bunch of code with help for drawing, audio, and input.
SOOOO many things so here's a list of great resources that you can check out.
Unity 3DUnrealGame MakerHTML 5 GamesLove2DRemember to start with something small so you can finish. No need for the MMOFPSRPG thinking till way later (and millions of dollars)
Also see if there's any game jams in your area to see if you can team up with someone who has made a game before. If not in your area check over at itch.io they have a ton of jams happening online all the time.