I’m aiming to set up and tweak the balance of a 2d world until I can balance it. An island that features monsters, soldiers, civilians, and resources all interacting with eachother automatically.
This sounds like a lot of content, especially for someone who is learning game development. Ambitious ideas are always good to have, but if you are talking about making your very first game, I would suggest to start really slow and dramatically reduce scope.
Before all that, for me step 1 is to make a world that just ticks along with Stuff happening. What software will be a good introduction to start building that, with plenty of advice I can Google, and with the potential to be able to layer on all that gameplay stuff later.
Pretty much any tool that can be used for game development can do this. Software recommendations are difficult, as they differ depending on taste. You can try out Godot, which is a GUI Game Engine, or you can build everything from scratch using OpenGL. This depends on your programming experience.
A good rule of thumb for first game projects is to make something really simple, like a tic-tac-toe or a pong clone. Working on something more complex while you are building experience, has high potential of creating burnout and discouraging you from finishing the project.