Your seat is too far back, and your bar is too low. Get the saddle centered fore-and-aft on the post, and pull the stem up.

If the mechanicals are in good order, a '90's rigid MTB is a good re-entry bike. They're modern enough to have indexed (rapidfire) shifting, but old enough so that they're pretty simple, and that makes them durable. 21 speeds (3x7) make a wide spread of gears for any terrain.

Lots of them end up with drop/trekking bars and narrow(er) 1.5" tires as touring bikes and long-distance commuters.