How can I iterate over the contents of a directory in unix without using a wildcard?

I totally understand what the problem is here.

I have a set of files, prepended as 'cat.jpg' and 'dog.jpg.' I just want to move the 'cat.jpg' files into a directory called 'cat.' Same with the 'dog.jpg' files.

for f in *.jpg; do
    name=`echo "$f"|sed 's/ -.*//'`
    firstThreeLetters=`echo "$name"|cut -c 1-3`
    dir="path/$firstThreeLetters"
    mv "$f" "$dir"
done

I get this message:

mv: cannot stat '*.jpg': No such file or directory

That's fine. But I can't find any way to iterate over these images without using that wildcard.

I don't want to use the wildcard. The only files are prepended with the 'dog' or 'cat'. I don't need to match. All the files are .jpgs.

Can't I just iterate over the contents of the directory without using a wildcard? I know this is a bit of an XY Problem but still I would like to learn this.