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.