That's why I never liked the look of Godfilla in the Japanese movies. That upright posture just screams IT'S A FAKE!
And the fact that it's projected on a movie screen doesn't? Or the fact that everything about it is physically impossible? There's no way any living thing could get that large, there was never any dinosaur like that in the fossil record, and heck, plenty of the movies contain blatantly supernatural elements. Of course it's fake. It's all imaginary. A lot of it is allegorical. It's not trying to be realistic in any way.
Would you rather that Kermit the Frog be a CGI creature designed to look exactly like a real frog? Or that Roadrunner cartoons be about a realistically rendered coyote and roadrunner behaving in scientifically accurate ways? (In which case it would be a short and grisly series, since coyotes can actually run more than twice as fast as roadrunners.) Lots of things are supposed to look unrealistic. Kaiju battles are essentially a form of puppet theater, an art form that has a long history in Japan and elsewhere.
That said, some of the later Godzilla movies made considerable improvements in the special effects. There are some impressive ones in the films of the '90s and early 2000s.
I'm fully aware that it's all fake.
I'm just saying that they should try to make it look like what it would really be like if it was real.