typo in first line corrected as noted by genresearch, apologies for the confusion
Copyright is not a cut and dried easy to explain thing. It also varies slightly between America and Europe so the internet can be a minefield when using images that may have copyright issues.
Copyright belongs to the creator of the work, in the case of images it remains in force for a period after the death of the photographer, any income from works (including images) is then payable to the deceased persons estate. Copyright doesn't automatically pass to next of kin.
Copyright holders can waive some or all of the rights available but only they can do so, someone in possession of an image (either the original, a re-print or electronically created ie scanned, e-mailed etc) does not hold the copyright and cannot grant the rights to anyone else.
Images can be "all rights reserved", that means they cannot be reproduced, re-published or transmitted either by any means including printing, scanning, e-mail or publishing on the internet.
"Some rights reserved" means the copyright holder has granted use of the image subject to certain conditions, this may allow re-production and/or transmission but then again may not. Before using or re-producing an image the rights available should be confirmed with the copyright holder.
The safest way to avoid any problems is to only use images that you have taen personally or those where it is known that no copyright exists. In any other case there as a risk of legal action.
Ancestry are pretty good at removing content that is in dispute as they can also find themselves in trouble from a legal standpoint but will probably require proof that the copyright exists and who it belongs to.