Brigade combat teams are not just infantry but also other combat, combat support and combat service support units and or soldiers.
For example, your typical airborne brigade combat team will have 3 infantry battalions, a cav squadron, a field artillery battalion, a combat engineer battalion, and a brigade support battalion. The idea being that a combat brigade can operate independently,
Even within the infantry company you will find non infantry, such as the fire support officer, NCO, and fire support specialists.
I’m not sure if that is what you are asking.