If there's a set of tools that can be used to solve most problems fast and efficiently I'm more interested than trying to brute force what I know into doing things it's not meant to.

Every tool has things it excels at, and drags at. The key is learning which tools are the best ones to use for a given problem. What kinds of problems do you want to solve?

I am hearing that you don't want to feel like you've wasting your time, and that's a valid concern.

Is your priority getting hired as soon as possible, making the most money, working on projects you feel ethically aligned with, etc? That's a good place to start.

Personally, my journey started in earnest when I was in Jr. High -- I started learning C and then C++. In HS I started learning HTML (this would have been 1995, so things were much simpler then and we all wrote tags in uppercase). Later it was Pascal and Ada, then Java, CSS, C#, Python, and then PHP and SQL for a while. (there are some other languages I'm forgetting in there, too) I started doing Ruby about 14 years ago and that's the majority of what I write anymore.

Saying all this to say: you will inevitably pick up many different languages over time.

I would really appreciate some recommendations for a stack that's simple and ships fast. 

If you want Simple --> LAMP stack, probably. PHP is procedural and straightforward. It emits basic HTML and CSS, and setting it up on a deploy target is a turnkey process.

If you want ships fast --> I still stand behind Ruby on Rails, but I'm very biased because I've been writing in it for over a decade. Here's a screencast of me bootstrapping a basic CRUD app, with validations, in an hour. https://www.youtube.com/watch?v=8VnAMofSCLc

If you want to do stuff with AI specifically --> Python is fine. Django is pretty popular too. Most contemporary languages have AI libraries at this point, so you can really pick whatever you like.

You're new, so you're going to make mistakes, and that's ok. Fuck around and find out.