Learning the guitar as a beginner is quite daunting and challenging. You must endure the pain of un-calloused fingers pressing against steel strings, and work tirelessly to train your fingers to contort in un-natural ways and put your hand in strange positions which you must develop muscle memory for.
Because of the many challenges inherent in learning guitar, it is important to create and foster an environment that will facilitate and contribute to as much of a rewarding experience as possible.
Old corroded dead strings will not sound nearly as pleasant as new strings. When you finally get that chord you have been tirelessly practicing - to ring out clearly, you want it to sound as pleasing as possible to offer a reward for your efforts. This is only one reason you will want to use new strings.
I recommend that as a beginner, you choose a set of strings that will be easier to play and minimize the pain as you develop finger strength and calluses.
To learn more about how to create your own finger friendly custom string set for beginning guitarist read this Easy to play custom string set for beginning guitarist
Good luck on your journey.