How can I exclude all subdirectories but include files of a directory in rsync?

Try this command:

rsync -a -f"- */" -f"+ *" /home/user/ destination/

man rsync

-f, --filter=RULE           add a file-filtering RULE

The rule to include all files* and exclude the dirs */

Another approach to use the regular copy cp

cp /home/usr/* /destination

you can get rid of the errors about dirs using redirection

cp /home/usr/* /destination 2>/dev/null

This will only copies the files inside your home without the directories

If you want to exclude all *.sh from all subdirectories:
-f”- */*.sh”