Forget that nonsense about a $2000+ bike to start with. You don’t know what you want so how can you make a good decision on a $3000 bike?
Spend $400 on a craigslist hardtail. Disc brakes, the right size. Get a helmet, duh.
Find the easiest unpaved trail you can. Have fun. goof around. Ride with other people. In 6 months if you love it then you can start trying your friend’s bikes. Get to a demo day early and try some dream bikes. Then you’ll know what you want and how to use it.