Coming back to Javik's original question, let me take a slightly different position, as a new diver, and a crappy swimmer...
I think Javik was confounding three different things: natural buoyancy, swimming ability, and learning scuba diving. You all have done a great job of showing that a lot of people are naturally negative (or much less positive than average), and it's possible to be naturally negatively buoyant and still a great swimmer. There were also some off-hand comments, from strong swimmers, about how they couldn't imagine why anyone who wasn't a good swimmer would consider learning scuba.
Well, I'm one of those people. All my life I've been a weak swimmer. As a kid, I couldn't pass some low-level swim class ("minnows" or "guppies" or "sea urchins" or some such), because I couldn't back float, no matter how hard I tried (big breath, arched back, etc.). In college, I started over with beginning swimming classes, which went well until I got to "intermediate" with the varsity swim coach, who just yelled at us to swim laps, and I couldn't keep up. In OW (for Javik, that's the introductory scuba course), things that others complain about (mask clearing, reg swapping) were easy -- my biggest challenge was flailing through 200m of breaststroke to pass the swim test. If you give me a wetsuit, mask, snorkel, and fins, in reasonably calm water, I feel great; and if you toss me in the deep end of a swimming pool, I won't drown; but still, if you asked me to swim 400m without any aids, I'm not sure if I could do it.
But... I got my scuba certification, and I
LOVE it! With scuba, I can finally be relaxed in the water the way I always wanted, but was never able to before. I can breathe whenever I want. I'm neutrally buoyant. (For Javik: on scuba, you have a buoyancy compensator, to which you can add or remove air, to adjust your buoyancy.) I've dived with sharks, watched gigantic manta rays dancing graceful pas de deux, speared lionfish from a tiny islet in Belize. Even though I'm still a crappy swimmer.
I know I'll never be half as good a diver as most of you, and compared to a lot of you, I probably really am a "crummy diver". But I've never crashed into a reef, and I get a lot of compliments on my trim. And on the last few boats I was on (typical vacation destinations), I'm starting to find myself one of the more "with it" divers. (BTW, a lot of my progress is thanks to all the helpful comments from you all here on Scubaboard
).
So, for Javik, or anyone else feeling similarly, I'd say: if you are comfortable enough not to freak out in the water, and you can pass the swim test, and you always wanted to try scuba, go for it!
(BTW, I'd love to become a better swimmer, and I've been carefully noting all the swim advice here. I'm certainly not discouraging anyone from learning to swim better. But I don't think you need to be a former competitive swimmer to become a safe and competent enough diver to enjoy a lot of fantastic diving (in benign conditions).)