I ride 100-150 miles a week on a road bike. I have close to 20,000 miles on it, and about 38,000 miles since I started riding in 2002. I love riding. I ride for fitness and also commute to work when I can. Do yourself a favor and spend the money for a really good bike --$1000-$3000 is the sweet spot for bang-for-buck. The things at wal-mart don't qualify as real bikes. There is a company down the road from me called Fezzari-they sell on line all over the country, but their factory is about two miles from my house. From them you can get a lot of bike without paying for a brand name. They can set you up with a mountain, road, or hybrid bike. Look at the gravel bikes too--they are a nice balance that will take you over all kinds of terrain.
If you have any specific questions, send me a PM, and I will share what I know. Be aware, however, that there is currently a worldwide shortage on bikes and wait times for new ones might take til August or September. It seems a lot of people are discovering cycling during quarantine.