This is all a bit confusing.
If you take a photo in a public place of pretty much ANYONE you own the copyright the second the camera photo/camera goes click in UK.
The subjects can be Kids(not yours) , adults, dogs, cat does not matter public place there is no issue so long as it’s for none commercial purposes.
If that image is then use for commercial purposes you need everyone in that image to have signed a model release. Otherwise you cannot use it for commercial purposes/personal gain.
So any image you take the copyright is yours.
If you post that image on Facebook / any social media platform the press can then “argue” this image has been released into the public domain and so as a piece of “news”, in the public interest it “may be used”.
BUT the copyright of the image is still the person who took the image and if the news paper or anyone else used it for advertising etc You could screw them for copyright infringement.
If your lucky depending on the size of the image used they may offer you £25.00 for the use of the image in the paper especially if they did not credit the original source but you will not be talking telephone numbers that’s for sure!
I am not a lawyer or legal professional just had a few images published over the years.
I don’t know how many court test cases have been used yet in regards to media using social media images.
FROM BBC
The re-use of material from the internet can raise legal issues of privacy and copyright. A strong public interest reason for using a photograph can help justify re-use without permission, but you should not automatically assume that pictures or video you are seeking to include can be used under ‘fair dealing’. Advice is available from BBC Lawyers.
BBC guidance of social-media-pictures