Yes, certainly people try to fit deities and other aspects from one culture into another, but it works just as well as using Canadian coins in the states. It probably is true that humans are very much alike and have similar needs and wants, but similarity does not mean sameness. Apples and oranges may both be fruits, but they re not actually the same. Neither are gods of different traditions. Trying to force something from one culture into a mold of another generally leads to making a pale mockery of the original, as well as taking away a lot of the original meaning.
Similarities can be useful, certainly.
However, they aren t the end of the story. Too many people seem to take the easy route, see a few similar details, and assume the rest of the story is also the same. Worse yet, a few details taken one way can lead to traditions, which too often go unquestioned and unexamined, like this whole business of Loki being considered the Nordic version of the Christian devil, when there are probably at least as many similarities between Loki and Christ, if not more. Nevertheless, even in mockery, there s a thread of truth. Unfortunately, these days, people seem to take mockery far too seriously.