Noob looking for a bike to get in shape with and eventually commute with.

First off, thanks in advance for taking the time to read this post and (hopefully) guide me in a general direction, as this entire process of finding a bike has been overwhelming.

I’m starting the bike journey to become healthier, but eventually will want to commute to work as well. Possibly do some longer rides once I build my stamina up.

Some specs about me/location/etc.:

Level of experience: none, except knowing how to ride a bike. Price range: under $400. Extremely open to secondhand/used. Location: Charlotte, NC. Relatively flat, some gradual hills. Paved roads. Purpose: fitness and commuting (6 miles round trip). Longer rides when I get in better shape. End goal is to bike everyday or at least most days. Me: 5’3”, 69 cm inseam

I’ve compared everything from a road bike to a fixie to a hybrid, to be left even more confused on what I need. Any input, advice, recommendations are welcome!