...I was trying to make sure that all would be viewable in the future.
In the old days one of the things we had to think about was what format to save things in if we wanted to be able to open them in the long-term future.
Both pdf and jpg formats are so ubiquitous that this isn't going to be an issue - there will be applications that can open and convert both formats so far into the future that none of us here today will ever have to worry about that issue.
In terms of choosing between them, jpg is a format which was designed for efficient storage of images. Pdf is a format which was designed as a format which allowed documents of various types (including images) to be viewed on the widest range of systems and applications.
An image has to be processed to put it into a pdf - the pdf acts as a kind of 'wrapper' around the image. That processing may include resampling, compression and cropping (depending on the application and settings). As a rule, processing an image in this way takes something away from it - either detail, size, or extent.
So converting a jpg to pdf is likely to degrade the image (though not necessarily by a noticeable amount), but more importantly, converting from pdf back to jpg can give a result very different to the original image.
Therefore I wouldn't convert jpg files to pdf unless the application I was using would
only work with pdf, or if opening a jpg file rather than pdf had such an effect on performance that the application becomes unusable.
However, most future problems can be avoided by always keeping a 'master' copy of the images as a jpg with zero or very slight compression, and having a 'working' copy in whatever format is needed for the application being used.
TL;DR - stick with jpg unless you have problems with them. If you do have problems, try and work out why.
