In Beresheet 9 it is written: Every moving thing that liveth shall be meat for you; even as the green herb have I given you all things. So if Noah had permission to eat any kind of living things, then why when the Torah was given, Elohim forbid many animals as non Kosher.
The commandments to the Jewish people contain many restrictions that were not given to humanity at large. This is one of them. The reason that the Torah had to explicitely allow meat to Noah was that it was forbidden to Adam (see Beraishit 1;29,30