[mementomori]

Can anyone recommend some less opinionated introductory resources to learn reinforcement learning that focus on first principles?

[blahblahblah10]

I would highly recommend Sergey Levine's course:

http://rail.eecs.berkeley.edu/deeprlcourse/

For a more mathematical treatment, there's a beautiful book by Puterman:

https://www.amazon.com/Markov-Decision-Processes-Stochastic-...

[ampdepolymerase]

I recommend Sutton and Barto

http://www.incompleteideas.net/book/the-book-2nd.html