Nobody has ever just taken up being a goalie later in life & made it to the top so just going "Lebron would make it easy" is ridiculous. He might, but it's never been done so the point is moot.
The best 'athletes' are running track & field at the Olympics. I'm talking Sportsman, really.
Ronaldo is a miles more impressive Sportsman because he's one of the best of all time in a sport tried & played by billions that is a mixture of athleticism AND skill equally. Soccer isnt a flawed sport that gives an absurdly large advantage to people born to grow to a certain height. If you havent started playing soccer from a very early age & dont hone your skills repeatedly from said early age, then you have NO CHANCE of making it to the top. The skill level required for any position cant be counterbalanced by ...."well you're 7 feet tall", or "well, you've never kicked a ball before but you can run 100m in 9.9 so you might make it to the Premier league".