The concept of a “patron” deity, or a main deity, or a “Parent” deity comes up a lot in Kemetic practices. Heck, it comes up often in any pagan/polytheist practice. Look at any online meeting place for polytheists, and you’ll find a number of people introducing themselves not only by their path, but also by the deities they primarily honor. It’s a way of categorizing ourselves, and a way of finding like-minded individuals. Is it necessary to have a primary deity? I don’t think so. Is it something that will most likely happen, one way or another? Probably.
I think it would be helpful to draw some distinctions in terminology, here. In Kemetic Orthdoxy, a “Parent deity” specifically refers to part of the outcome of the Rite of Parent Divination, which is a rite of passage into the Kemetic Orthodox faith, in which the deities who are responsible for an individual are revealed by divination. The Parent deity (or deities, up to two) tends to act as a patron deity for the person, though not always. People who have had the rite done refer to themselves as children of whichever god or goddess. It is specific to Kemetic Orthodoxy, and is only necessary if you’re going to make that your primary practice.
A patron, or main deity, is a more general term for the god one seeks the most interaction with — the most offerings made, the most prayers said, the most devotion given. Anyone can have a main deity, or a patron deity. Anyone can forge a close relationship with a god. For that matter, anyone can call that deity their “Parent” deity – it is only within Kemetic Orthodoxy that the term “Parent” carries a ritual meaning as well as denoting a relationship.
Terminology aside, I think most people will find themselves with a main deity or deities. It may not be that there is one singular god who is completely in charge, but given the number of gods in the Kemetic pantheon it is highly unlikely They will all get equal treatment. There are a LOT of gods in Kemet with a LOT of different personalities. Simple logistics and interpersonal preferences dictate a need for selecting appropriate deities for oneself. Sometimes this is as simple as self-selection: finding the deity whose domain or personality suits you best and approaching Them. Sometimes, deities come knocking and tell us, in Their own way, that we belong to Them. Finding one’s main deity is an intensely personal process, I believe. Nobody can tell you how to decide which gods to honor. If you’re just starting out, and you want to honor Yinepu, I believe you should. You might find that as you get to know Him, other deities step in and draw your attention away from Him. You might find that you form a deep, personal relationship with Him. You may find that He directs you away, to other deities.
It’s a journey, and it’s one with many steps and turns and twists. You may start with one deity as your patron, and then find others entering your practices. You may undergo the RPD expecting one Parent, and be surprised by a second Parent and several Beloveds. You may begin your practices honoring several deities, and find yourself gradually focusing on one. I started my practices honoring Yinepu and wound up with Wepwawet; I denied that I would ever worship Sekhmet because I wasn’t “cool enough”. My advice to beginners? Be bold enough to approach the gods; be open enough to hear Their reply; be humble enough to remember that the god you want might not be the one for you; be proud enough to acknowledge when They are calling you.
carrying their light 
Sometimes your ‘Mother,’ is just as much a teacher as your ‘Uncle.’ Your Mother aids in growth, but the Uncle teaches. I hope that makes sense.