Yes they can. If YOU didn't take the photo, give a [source] link to the image or the website at least.
I do that with EVERY IMAGE, even though I get EVERY (non-original) image from Unsplash dot com, or Pixabay dot com, both of which state just what you posted above.
Work licensed under a Creative Commons license is governed by applicable copyright law.[10] This allows Creative Commons licenses to be applied to all work falling under copyright, including: books, plays, movies, music, articles, photographs, blogs, and websites.
creative commons licenses
It may not be REQUIRED, but it IS common courtesy to at least give your readers the opportunity to go and check out your sources, there might be more there of value to them than that which you have shared.
اس کی ضرورت نہیں ہوسکتی ہے ، لیکن کم از کم اپنے قارئین کو جاکر اپنے ذرائع کی جانچ پڑتال کرنے کا موقع فراہم کرنا عام شائستہ ہے ، اس سے کہیں زیادہ قدر ہوسکتی ہے جو آپ نے شیئر کی ہے۔