That was Batman in disguise; the truth of Killer Croc is that he's 'only' six feet and five inches tall, that he possesses neither snout nor tail and that his fangs are the result of deliberate dental manipulation on his part (because Jones knew that it's kind of hard for a Crocodile-man to scare the hell out of people without fangs, especially in the wrestling ring and Croc is smart enough to use his intimidating appearence for all it's worth). It's also true that, when you get down to it, if you hand Croc Batman on a plate he'll beat that sucker's head into pulp with a real big rock, rather than default to a death trap or just plain waiting for the Bat to come around, then boast.
If that makes him stupid then he's d--- glad he was born dumb.
Here's the real deal on Killer Croc; he was a kid born out of wedlock to a mother who died in childbirth, leaving him with an aunt who was more scourge than saviour, as well as a hereditary skin disease that cursed him with a resemblance to a human lizard that only got stronger with age. For all of his early life he wandered from emotional abuse into petty crime into the penal system into physical abuse and then back on the wheel of misfortune again - with a brief spell as a circus strongman-freak and freakish wrestling heel the only remission, made all too brief by the fact that Jones has absolutely no real idea of how decent people treat each other because no-one in his experience ever treated him decently.
He drifted back into crime and finally decided to live there because the Underworld was the only place he's ever found which treated being big, scaly, good at legbreaking and freakishly scary as a good thing - he came to Gotham because it's still the only place on Earth where a freak can become a kingpin and Killer Croc wants to be Kingpin in Gotham.
Does it surprise you that Croc has big dreams and a comprehensible plan to make them reality? Well, that's not unfair, since it sometimes surprises even him that he actually sticks with them - because Croc is well aware of his strengths and his limitations because they ARE his plan: he's tougher than the smart guys and smarter than the tough guys (he's also more stupid than the smart guys and not quite as tough as some of the toughest guys, but he does his best to compensate or just endure the hard knocks).
He's going to make sure what he has works for him and work his way up to the top spot as fast as he can before someone kills him. Nobody except Croc believe he'll make it, but he doesn't give a d---; the only school he ever graduated was the school of hard knocks and the reality of defeat scares him less than the idea of being a never-ran, the prospect of failing just because he refused to pucker up and take his hits like a man.
Croc has been hurt by experts; he's been condescended to by genius; he's suffered just about every sort of reverse that you can imagine, all pretty much alone and he's still biting back - in all honesty, he's suffered the consequences of so many failures that the Underworld is a little in awe of the fact that he can keep coming back for more punishment and quite frankly that attention keeps him going.
People may laugh at Croc and scream at Croc but no-one ever ignores him.
Alright, that should have given you some idea of Croc's flaws, his toughness and his motivation so now let's discuss methods and personality:- when you get down to it Killer Croc is a wonderful henchman, a horrible boss and a passable customer because the only worldview that makes sense to him is Alpha-Omega; you're either the Big King or the Help. The former gives the orders, the latter obeys and if the latter does what the former tells them just right then the Big King will repay - disobey and bad things happen.
When Croc works for somebody, he keeps his own plans on the backburner and does what he's told with no frills, no complaints and no back-stabbing; if he's the boss then his mooks tend to suffer because he suffers from a chronic need to prove he's the boss and tends to prove himself by biting lumps out of people who tick him off. Unsurprisingly he tends to be more popular with Master Villains than with his peers - part of the reason he keeps getting invited to the Penguin's card games; Oswald appreciates the service he has rendered in the past and keeps trying to put him on retainer.
Croc keeps replying that he can't because one day the Penguin will be working for HIM; The Penguin, being a gentleman crook treats this as a pleasantry rather than an excessively-optimistic statement of fact.
On a related note, Croc is king of Gotham Muscle-men because it's easier for him to think his way around someone stronger and dumber than he is than it is to get close enough to the Masterminds to crush their skull before they out-think him; if you're smarter than Croc then you're more than smart enough to stay out of reach because what Killer Croc grips doesn't live long. A street-fighter with a grounding in wrestling, he used to kill alligators with his bare hands as a party trick after hours (part of the reason the Circus kicked him out and that wrestling ring picked up his services), if he gets his hands on you, you'll need more than tricks or simple strength to break free - witness the fact that the only man known to have broken his grip is Bane, someone both smarter than Croc is and just as strong.
When I say the only man, I mean ONLY - the first time Batman took on the Croc, when he was young and a lot more arrogant than he is now, Croc was lucky enough to seize the faint chance of a fair fight and d--- near killed The Dark Knight; if it hadn't been for the fact that Croc wanted to make an example of him, The Bat would never have been able to escape, recover and then arrange a rematch in full view of the Arkham Asylum luminaries Croc had managed to assemble with the prestige he'd earned the hard way - cheating for all he was worth, Batman won by a landslide and by turning a mud pit into an operating table.
Croc has yet to match that achievement, but he's come dangerously close.
One final note; hard-headed and thick-headed as he may be, Croc is no more stupid than any other career criminal who has lasted as long as he has in Gotham; in addition to being the toughest muscle-man, he's also the best criminal diver in the business, scuba or free diving and quite bluntly he OWNS the undercity - a strange network of sewers and bits of Gotham that the city has built over in it's climb towards the skyline, with a population of the derelict and forgotten whom Croc dominates effortlessly.
As Croc likes to put it, he already controls the Gotham Underworld - now all he needs to do is win control of the Criminal World and he can die happy.