Pathfinder

So, I don’t have any of the books and I’ve never played, but I am interested in learning PF. Anyone want to DM a beginner?

Try thetrove.net for the books. They're free. I've never played it and I wouldn't mind giving it a try either.

While The Trove does provide fine sharing of the books, these are not authorized sharing and there is undoubtedly a copyright violation issue.

Paizo does provide legal online access to the ruleset through their PRD, at http://legacy.aonprd.com/

Qralloq speaks the truth. Also, as someone who has played a lot of Pathfinder, all you'd really need is the core rule and a bestiary.The core game is easily robust enough to keep you going for a loong time.

As an aside, the ink Qralloq indicated has both the 1e and 2e rules for Pathfinder,as well as the core game for Starfinder.