John Atkinson has rightly expressed cautions. The legal position is complicated. And it is not just about copyright law - it is also about the terms and conditions of each website that hosts images. Those also need to be checked out.
A further complication is that some sites clean up some images of scanned books and documents. That cleaning up gives them legal rights. For instance, I believe Ancestry has cleaned up some images.
Unless one is absolutely certain that it is legally safe to use a scan of a book page or a document, the best course is just to link to the image, give a proper citation (which will be to the book or document itself), extract the relevant facts from the page or document, and incorporate them in the biography on the profile. The facts and citation, with a link to the image, should be put on the biography even if the image is added.
When Projects review or work on profiles, they will often check whether it is clear that it is permissible to use images. If it isn't clear, the images are likely to be removed.