There are nine ways in all to get on base. That list of 23 ways is wrong, wrong, and more wrong because it has redundant ways and because it has just flat-out wrong ways.
The ways to get on base without getting a hit are:
(2) Hity by pitch
(4) Fielder's choice
(7) Wild pitch (uncaught third strike)
(8) Passed ball (uncaught third strike)
Now to debunk the "23 ways" fiasco...
(1) Fan interference is a base hit.
(2) There is no such thing as fan obstruction
(3) Illegal pitches resulting in a walk are walks (duh!)
(4) The batter is not awarded first base if the pitcher fails to deliver within 20 seconds
(5) An intentional walk is a walk (duh!)
(6) Catcher interference and "fielder interference" are one and the same: interference
(7) A fair ball touching an umpire that results in a batter-runner being awarded first is a base hit
(8) A fair ball touching a runner that results in a batter-runner being awarded first base is a base hit
(9) A "dropped" third strike is a passed ball
(10) "Substitute runner" is a smart-butt response and not within the intent of the question
(16) Suspended game, blah, blah, blah (No. 16 on the list) is bogus because that's simply a substitution (see preceding answer)
(17) A fielder's choice is a fielder's choice is a fielder's choice (Get it?)
(18) Preceding runner called out on appeal will not get the batter-runner first base (I'm totally flabbergasted by this ridiculous claim)
(19) Preceding runner put out is a fielder's choice (duh!)
(20) Attempted sacrifice bunt fails to advance a runner is a fielder's choice (duh!)
(21) A sacrifice fly that is dropped is an error (duh!)
It's unbelievable that this "23 ways" ever made it online and that people actually believe it.
14-year umpire; Senior League Baseball World Series information director; Official Baseball Rules: 10.00