You can create a shared folder and set permissions so that all users can access it. For convenience you can also create links in users' home directories to that folder.
Go to /home
and make a new directory
sudo mkdir /home/pictures
Then set permissions and ownership to make the folder accessible and writeable by all users (note that this is a security risk - it makes it possible for any user or process to modify the contents of the directory and add or delete content)
sudo chmod 777 /home/pictures
sudo chown nobody /home/pictures
Then add the content as desired.
A more secure method would be to create a group with all real users, for example:
sudo addgroup pictures
sudo adduser user1 user2 pictures
And set the permissions of the /home/pictures
directory like this:
sudo chown :pictures /home/pictures
sudo chmod 775 /home/pictures
With these settings, only group members and root will be able to write to the directory, though it will remain readable for guests and other processes (so a program that set your wallpaper would be able to read from it, for example).
Then you can create links to access that folder, or user can create
ln -s /home/pictures /home/user1/Family_pictures
When user1 tries to access Family_pictures
they will see the contents of the shared directory,