We went from a micro-blob to human while numerous species just stopped evolving for 500m years?"
Which illustrates one tenant of evolution theory: evolution won't fix what ain't broken.
The basic crocodile body-plan has worked well all these years, while many others went extinct.
But it's wrong to suggest there's been no crocodile evolution, as the fossil record clearly shows many varieties on the theme:
Crocodile evolution from Jurassic (200 mya) on: 
"Here is a list of the most notable crocodiles and phytosaurs, living and extinct:
- Aegisuchus Better known as the "ShieldCroc."
- Allodaposuchus This "eusuchian" prowled the rivers of southern Europe.
- Anatosuchus Otherwise known as the "DuckCroc."
- Angistorhinus A crocodile-like phytosaur of the late Triassic period.
- Araripesuchus This long-legged crocodile hunted its prey on land.
- Armadillosuchus Otherwise known as the "armadillo crocodile."
- Baurusuchus A land-dwelling crocodile of Cretaceous South America.
- Bernissartia One of the smallest of all the Cretaceous crocodiles.
- Carnufex Its name is Greek for "butcher."
- Champsosaurus A crocodile-like reptile of the late Cretaceous period.
- Chimaerasuchus The first vegetarian crocodile ever to be discovered.
- Culebrasuchus This crocodile sheds light on the geography of the Americas.
- Dakosaurus This fierce marine crocodile had a dinosaur-like head.
- Deinosuchus One of the biggest crocodiles of the Cretaceous period.
- Desmatosuchus A crocodile-like archosaur with a fish-like head.
- Dibothrosuchus A dog-like sphenosuchian of early Jurassic Asia.
- Diplocynodon A prehistoric alligator of western Europe.
- Doswellia This may (or may not) have been one of the earliest crocodiles.
- Erpetosuchus This tiny reptile may have been the ancestor of all crocodiles.
- Geosaurus This aquatic reptile may have spent its entire life in the sea.
- Goniopholis A widespread crocodile of the late Jurassic period.
- Gracilisuchus One of the most dinosaur-like of all the Triassic crocodiles.
- Guarinisuchus This marine crocodile thrived after the mosasaurs went extinct.
- Kaprosuchus This "BoarCroc" had some very big teeth.
- Mesosuchus This "middle crocodile" was a confirmed vegetarian.
- Metriorhynchus One of the most common crocodiles of the Jurassic period.
- Mystriosuchus This Triassic archosaur looked a lot like a modern gharial.
- Neptunidraco "Neptune's dragon" is the earliest identified metriorhynchid.
- Notosuchus Did this ancient crocodile have a pig-like snout?
- Pakasuchus This tiny crocodile had distinctly mammalian teeth.
- Pholidosaurus This proto-crocodile is a taxonomic nightmare.
- Pristichampsus A hooved crocodile of the Eocene epoch.
- Protosuchus This land crocodile competed for prey with early dinosaurs.
- Purussaurus A giant caiman of the Miocene epoch.
- Quinkana A terrestrial crocodile from Down Under.
- Rhamphosuchus Once thought to be the biggest crocodile that ever lived.
- Rutiodon This crocodilian's nostrils were located on top of its head.
- Saltoposuchus This "leaping crocodile" spent most of its time on two legs.
- Sarcosuchus A Cretaceous "SuperCroc" that put modern crocodiles to shame.
- Simosuchus This ancient crocodile had an unusually short skull.
- Stagonolepis This crocodile-like archosaur was actually a vegetarian.
- Steneosaurus An ocean-going crocodile of the Mesozoic Era.
- Stomatosuchus This giant crocodile fed on tiny plankton, like a baleen whale.
- Terrestrisuchus Otherwise known as "the greyhound of the Triassic."
- Theriosuchus This "beast crocodile" straddled the Jurassic and Cretaceous periods.
- Tyrannoneustes This "tyrant swimmer" cut a very crocodilian profile.
- Xilousuchus One of the earliest archosaurs in the fossil record."
My point: evolution has provided many different forms of crocodiles, though never an ability to escape it's basic ground-hugging water-living shape.
Other early life forms did go on to much greater varieties.