TLDR:
Bakgrund: Förhistorisk dinosaur som överlevde (precis som Nessie :))
Motivation: Har förändrats över tiden, från en varelse som ville vara ensam, till ett våldsamt och ondsket djur, till en enstaka jordens frälsare, till ett stort territoriellt djur.Fullständigt svar:
För att vara ärlig har många av dessa frågor förklarats väl (och refererade) på Wikipedia-sidan :
Within the context of the Japanese films, Godzilla's exact origins vary, but it is generally depicted as an enormous, violent, prehistoric sea monster awakened and empowered by nuclear radiation.
Så det kan ses som att det visserligen är befogat med nukleär strålning (och så var väldigt aktuell när den släpptes), det var inte skapad med det. Faktum är att hans ursprung är mycket tidigare :
In the late Cretaceous era (70 million years ago) there was a species of therapod dinosaur resembling a large Tyrannosaurus, but with special amphibious adaptations which allowed it to swim between the islands upon which it hunted. This dinosaur species has been dubbed "Gojirasaurus". A minimal breeding population of gojirasaurs somehow survived the great extinction event which killed off other dinosaurs and continued into the modern era...
Denna beskrivning talar med bakgrunden till Godzilla i 2014-filmen, som du specifikt hänvisade till. Detta citat är från reklam för en officiell leksak för filmen :
Possibly the last of an ancient species of giant amphibious creatures that evolved when the surface of the Earth was over ten times more radioactive than it is today. GODZILLA can create his radiation stores into a violet, focused exahlation of atomic ray. Rarely seen, but spoken of in ancient island mythers, "Goijara" was last spotted in 1954, when the U.S. Navy encountered him and attempted to kill him with an atomic blast in the Pacific Ocean. Since then, the giant creature has been living in the deep ocean - until a theat to his survival from an ancient foe forces him to appear.
När det gäller huvudfrågan på dina frågor - hans trovärdighet och motivation - anser jag att alla filmer måste undersökas för att se hur hans "karaktär" har utvecklats och förändrats. Återigen från Wiki:
Godzilla's allegiance and motivations have changed from film to film to suit the needs of the story. Although Godzilla does not like humans, it will fight alongside humanity against common threats. However, it makes no special effort to protect human life or property and will turn against its human allies on a whim. It is not motivated to attack by predatory instinct: it doesn't eat people, and instead sustains itself on radiation and an omnivorous diet.
When inquired if Godzilla was "good or bad", producer Shogo Tomiyama likened it to a Shinto "God of Destruction" which lacks moral agency and cannot be held to human standards of good and evil. "He totally destroys everything and then there is a rebirth. Something new and fresh can begin."
Ovanstående stycke (med hänvisningar borttagna) visar att Godzilla tenderar att följa ingen mästare men själv, som han anser lämplig. Detta diskuteras vidare på Godzilla-specific-Wiki :
Godzilla, in the original film...is an animal with semi-sapience that stumbles upon human civilization without any malicious intent, only destroying man-made structures or obstacles like buildings when the humans provoke him...In [later films] Godzilla is a malicious entity created from the restless souls of the dead from World War II. [Since then he has] developed as a character, and has since become a savior of the Earth, saving the world from other monsters like King Ghidorah, the Showa MechaGodzilla, etc.
According to Mothra's Shobijin's translation of Mothra, Rodan and Godzilla's conversation in Ghidorah, the Three-Headed Monster, Godzilla only "hates humans because they hate him."
In Legendary Pictures' Godzilla, Godzilla's behaviour seems to be that of a territorial animal.
Godzilla har sålunda förmåga att bekämpa och försvara sig själv och till och med rädda människor, men vill i hög grad skydda sig och sitt territorium.
Gareth Edwards, filmdirektören, bekräftade denna idé i en intervju där han frågades vem "hans" Godzilla skulle vara om det var en person:
His answer: the last samurai.
"He's an ancient warrior who's the last of his kind, and his kind has long since died out," Edwards says of his take on the legendary creature. "He lives a very solitary lonely existence and he's very happy to keep away from everyone, but we keep doing things to force him to return and put things right." ...
To see Godzilla's motivation and understand his reactions "when he was doing his thing," Edwards adds, "we dialed some more personality and made him a lot more human than we thought we would."
Så du kan se att regissören syftar till att göra honom territoriell, men i slutänden "mänsklig" i naturen - en väktare som vill vara ensam, men fortsätter att återvända för att skydda oss (ett ganska vanligt tema i många superhjältar filmer nuförtiden).