All of the bikes you listed are cheap -- but very cheaply built. They will be heavy, crude, and have pretty lousy performance. If you took any of those bikes to a bike shop for repair, they'd tell you that they're not worth their expensive time to fix, and they might laugh. Those bikes would all be strong enough for an overweight person; their heavy frames are at least rather strong.

HOWEVER, some folks find happiness on cheapo bikes; there is a whole thread somewhere on this site about how the GMC Denali can be a good bike. Those same folks are competent at repairing and tuning the bike for better performance, and that matters a lot.

As-is, any new bike at that price level will probably be indifferently built at the factory and then incompetently assembled at the store. You'd have to lube it and tune it to make it decent, so I would only recommend a cheapo bike like that if you're a competent bike wrench.

Fixie? Do you ride fixies? They are quite different than a bike that freewheels (can be pedaled backward). Don't buy a fixie if you're not already riding one.

Where will you be attending college? If it has hills, you probably don't want a fixie or even a single speed. Especially since you said you're a bit overweight, you will really appreciate multiple gears.

In my experience, a cheapo new bike is just a temporary fix; it will break or start working poorly within the year and you won't want to spend the money to fix it. Then it gets dumped like all the cheapo bikes you probably see around town.

The best cheap bike to get is a used one, but it's tough to wade through craigslist and find a good deal. In general, a ten speed from the 80s or 90s would be a more competent bike than the ones you linked.