Copyright ownership of old original negatives

I own through purchase (payment) old original photo negatives, which are from the 1950's through 1980's

The images have not been published.

The original author is not identified or identifiable, as no identifying information regarding the originating (amateur) photographer is present or available otherwise. Some images have been purchased from other (third party) collections.

Most of the images originated in Canada (and I am in Canada).

With it being essentially impossible to find out who took the images, since I own the non-copied originals, do I own the copyright or all rights to the original images?

Is transfer of copyright implied through the act of selling the original images?

What if someone else later fraudulently claims to own the copyright but does not possess any evidence such as an original master image?

Thanks very much for your assistance