The common recommendation you'll get as a new biker is to get a used bike to see what you like. Then if you start to really enjoy biking, get something nicer that's more suited to your needs and desires.

You're looking at a new 'used' bike so you're already on the right path.

What it really comes down to is how much you like it? You can probably find an actually used bike on Craigslist that is suitable for you in the $100-$250 range. What's more important to you? Saving money or getting something new? (Neither answer is wrong)

If you really like the $375 bike and you're sure you could like it for a couple years, it sounds like a winner.

As far as other stuff....helmets are a personal choice. On a trail, I only wear mine to be a good example to my kid. When I ride on the street I never leave home without it, make sure the strap is tightened correctly, and have a blinking red light strapped to the back of it.

A bike multi tool is handy. It's like a swiss army knife for bike tools. Has all the commonly needed allen wrench sizes. You'll want to adjust most things on your bike after riding it a while to make it fit you better (angle of the shifters and brake levers, seat position, etc) A bottle cage is usually a good idea for carrying water.