"Abandonware" is not freeware, and the Jazz Jackrabbit games were never freeware. Sure, you could find them in some "abandonware" sites, but abandonware is nothing more than a grey area some people made up to justify piracy. Though I don't work with video games, I do work in the publishing business, and I can say, with all certainty, that so-called abandonware has no legal standing whatsoever. None. At all. Never had, never will. If you're downloading an "abandonware" product, you're downright pirating. Whether you feel good or bad about that is not up to me to say, but it *is* just piracy.
Unless the rights owner makes the product freeware, which the Jazz Jackrabbit games *never* were. You can still find shareware versions throughout the internet, but shareware is not freeware, it's basically a "demo" locked version of a game so that players could try it out before deciding whether they wanted to buy the full version. Shareware is legal, but it's not the full version of a game.