I'd get an AR, before you can't.
@entropy has an excellent plan.
Labnoti usually isn't wrong, per se, this time he is. No one is going to fundamentally change the sport by yelling the sky is falling trying to scare men that already know bullets are made out of lead.
Starting out anywhere other than the beginning is counterproductive.
The beginning is rimfire.
And everything learned on a rimfire completely translates to any other firearm. Especially the safety part. And the cleaning.
A used rimfire rifle will be an inexpensive education.
Shooting it at 200 yards is the same as a .308 at eight hundred.
There is a lot you can learn from it.
A rimfire pistol is as much a joy, too.
(Buckmark, Ruger MK4)
Really which to start with is a personal choice. I started with pistols.
A Chiappa 1911-22. (I wouldn't recommend them. Not terrible, not good either.
)
Welcome to the forum. And to a new hobby/sport.
And definitely look into competition.
"Practice" is a great excuse to go shoot.
And be a pest.
Some of us have a broken shoulder from ditching a bike and can't shoot anything right now. Let me... I mean them, live vicariously through your posts, for a few more weeks...