Is baseball a sport that a good athlete who has decent athletic ability can learn how to play and excel in?

Start by "walking to" one of your college's baseball pitchers and asking him to throw a ball to you at 80 mph while you're holding a bat trying to swing and hit it. Then standing in centerfield - see how far and accurately you can throw a ball towards home plate. Give it your all.

Decent athletic ability doesn't always translate to excellence in a sport one never played.

Most guys start playing baseball when they're four or five years old and have been mastering the art of hitting or pitching since that age. The coordination and skill that it takes to pull it off is great, but not insurmountable.

No, if you're not athletic, pretty much the only position you can play is First Base or Designated Hitter.

I can't think of a sport that would be harder.

Maybe ice hockey, if you can't skate.

If you have to ask I am going to assume you've never played it.

Sorry, but baseball is NOT a sport that someone can just "pick up".

Keep in mind that hitting a baseball is regarded as the most difficult individual act in sports - they hand you a round bat, then throw a round ball at you at 90+ mph and tell you to hit it squarely.

And keep in mind that the players you will be competing at will have had a head start. Even if they are playing "junior varsity" (whatever the hell that is. I've never heard of it at the college level)

Not that it would be impossible, but I'd say it's an extremely long shot. You are just way too far behind.

Try slo-pitch softball with some park district team instead.