Hi LearningRPA,
Emphasizing the word "generally", Work Queues are used when there is large amount of data. Its full purpose can be achieved by distributing the data (or cases) from the Queue to be accessed by multiple bots at the same time and hence complete the task at a faster rate.
You can still use Work Queues by using a single bot. Work Queues have their own features like adding tags to the cases, updating statuses to the queue items, better monitoring and reporting of the cases, setting priorities, deferring cases to be processed at a later stage, etc.
From your post it says that there are only a couple of Excel files and couple of cases in them. So without work queues sounds suitable. But it will be up to you to decide whether to go ahead with queues or not depending on if you want to make use of the above features or not, or perhaps use it for understanding how queues work. Also, BP has the Ms Excel VBO business object which can read the files and easily update their statuses within the files without using queues.