Yes - data files should never have the exec bit set.
But - before you venture into a chmod -x folder -R yo need to understandt that folders need the exec bit to allow navigating the folder.
Ensure you are executing this inside the top folder containing the files and folders you copied
You may need - to set the owner and group - $USER:$USER is an environment variable holding your current user:group example monkyboy:monkeyboy. If the files are copied from a mix of unknown users - below command can be executed with sudo -
WARNING never do this in a system folder e.g. /. Always limit to files and folders you have write access to - thus ONLY inside your $HOME
chown -R $USER:$USER
find . -type f | sudo xargs -d'\n' chmod 664 # file permisson to rw for user and group and ro for other
find . -type d | sudo xargs -d'\n' chmod 775 # folder permission to rw for user and group and ro for other
find . -type d | sudo xargs -d'\n' chmod +s # set defaults for new files in a folder to inherit the folder permission