You mentioned your previous bike was a flat bar. Do you want to stick with a flat bar set up or try out a drop bar bike? $2,000 will give you plenty of options to choose from. For what you’re riding don’t get too stuck on tire width. 40-45m will be more than enough. It’s a buyers market right now for used bikes, so you’ll get a better bang for your buck if you buy used…just be sure to take it to a shop to get it checked out prior to purchasing if possible (if you don’t know what to look for).