The "primaryness" of a source emerges in relation to the researcher's engagement with it. The UC Berkeley Libraries define primary sources as "either created during the time period being studied or...created at a later date by a participant in the events being studied (as in the case of memoirs)."
(source: Finding Historical Primary Sources: Getting Started, last updated 8/12/18, http://guides.lib.berkeley.edu/c.php?g=4409&p=15606)
When determining primary sources for your research, it's helpful to give yourself a historical context that defines your search. This could be a range of dates. It could also be determined by geographical sites of origin. You might also be interested in a specific type of source. Some examples include:
Databases and digital repositories can offer a multitude of paths to potential primary source material for your research. In addition, you might want to try searches in the CLIO: Catalog or Articles, limited by date of publication.
Artstor is a searchable database of digital images and associated catalog data from museum, archives, galleries and libraries from around the globe. ARTstor documents the fields of architecture, painting, sculpture, photography, decorative arts, design, anthropology, ethnographic and women's studies, as well as many other forms of visual culture. Users can search, view, download and organize images.
Consists of four components: Spiritualism, Sensation and Magic; Circuses, Sideshows and "Freaks;" Music Hall, Theatre and Popular Entertainment, and Moving pictures, optical entertainments & the advent of cinema. Includes full-text, full-color reproductions of books, ephemera, handbills, pamphlets, photos, posters, programs, scripts, and other types of materials. Coverage is most extensive for Great Britain; but there is also a fair range of materials for the U.S.A.