How can I make artifacts available to the QA team with a user-friendly UI?
It seems to me that you're looking for an artifact store such as Nexus or Artifactory.
Both solutions have Jenkins plugins which will simplify the process of uploading your artifacts to them.
You can find an example as to how to upload artifacts from your Jenkins pipeline to Nexus in this link and an example for Artifactory in this link.
Both solutions are very common and relatively easy to manage and use and are known by the community for a long time so you can find many tutorials that explain how they can be used and benefit you.
Then, you just need to allow your QA team read access to the relevant artifacts repo and they can download whatever version of the artifacts they need.