To really excel within the ranks of the Army, must I serve in the infantry? Do I need a CIB/EIB, like the Chief and SMA?

Many of us 11B have no CIB. You can make a success of any MOS you desire, but you have to know what you really want. I had two goals: Get a retirement, make SGM. I made both. I could have made CSM, but I didn't want it. What do you want? Then you have to focus to get it. The road is not easy and you will probably have to make many turns in your career - I did. You will not always get to do the things you want to do because there are goals you want much more. NCOERs, ratings, don't want for someone to do them, stay on top of your Chain of Command. Getting assignments, reach out and get them - sometimes they are not the most glamorous, but it is the experience you want. Do your promotion packets. Education will play a major factor. When it comes down to it, it is you who will hold yourself back or you who gets you moving.

No one joins the Army to be a general. You join the Army to serve and lead. If you do it well enough you will promote. As for being infantry. It is a field that produces many General officers. Just as a alibi I am an infantry officer with a CIB and Ranger tab. The reason why you see so many generals that are infantry is because the Army is based around the Infantry. We are the heart of the army and Generals will command large infantry units in combat. In the army all the major divisions in the Army are infantry such as the 82nd and the 101st. If you were to take a job like signal officer there are no divisions are major commands in deployable units. You would have cyber command but you will never see a signal General command maneuver units. The Army is just not set up that way.

Do a job that you love to do. That's the best way to excel. Only you can determine what success means to you, and your idea of it will likely change over the course of your career.

Clearly not... SMA Raymond F. Chandler, SMA Kenneth O. Preston, SMA Jack L. Tilley, and SMA Robert E. Hall, the previous 4 SMAs, were non-infantry Soldiers.

That said, it makes sense you see a lot of leadership with CIB. EIB and/or Tabs because there are more leadership positions for those individuals. Most major and key positions in the Army are Combat/Maneuver commands, because the central role of the Army is Combat/Maneuver.

You can excel in the Army regardless of your role, but just as Rated members (Pilots) are central to the Air Force command structure as the Air Superiority branch, and Surface Warfare officers are central to the Navy as the Sea Power branch, Infantry and other Combat Arms leaders are central to the Army structure as the Ground Warfare dominance branch. It wouldn't make sense for most Navy leaders to be pilots, for most Air Force leaders to come from Security Forces, and it wouldn't make sense for most Army leadership to be drawn from non-maneuver branches.

It's not about fairness, it's about proper preparation for the job.

Pick combat arms if that is what you want to do. Originally, I went Military Police. I eventually transferred to Armor in the California Army National Guard. I went to the Armor Captain's Career Course. I later went to Civil Affairs in 2006. I have a diversified background. The LTC I just commented about did not diversify except being an OC-T. Nothing wrong with following your dreams. Just My Honest Opinion.

No, just do your job, and take pride in a job well done, a combat patch applies to any MOS,,,

Check out GEN Ann Dunwoody (Quartermaster Corps).
She doesn't have a CAB either.
https://en.wikipedia.org/wiki/Ann_E._Dunwoody

It is interesting that you ask this. I just heard from an outgoing lieutenant colonel who was our Deputy Brigade commander and served well and received excellent officer evaluation reports but yet he did not make full bird colonel and he is retiring next month because he is hitting 28 years as an officer. He said he's always stuck to be an armor officer always combat arms and that was his biggest mistake. He said he only knows one combat arms officer who made it to one-star general. He is referring to our former Brigade Commander. He suggested that you diversify into other branches of the army to make yourself more marketable. Our audience in our training command is predominantly made up of senior captains, Majors and Lieutenant colonels. I'm sure many of you will disagree on this opinion of his. He didn't go into civil Affairs or psyops or Branch transfer into Logistics. Maybe this would have helped him go to get to Colonel. The Brigade Commander had some parting words of praise for him saying how the outgoing Deputy Commander was five steps ahead of him and already had taken care of his first five questions about the unit and the Brigade Commander was scratching his head saying he can't believe he did not make O- 6 and he will be missed

To succeed what you could do is to break your butt doing your best, quietly do much more than is asked of you. Take it easy, do not always be the first to respond, save your strengths for when a problem arises! Maintain a superb appearance and conditioning; when a problem arises that you can solve/conquer- go DO IT! Keep your mouth closed - unless you are absolutely correct. Do not presume to advise those appointed over you! Save their ass from the fire if need be, and shaddup!