When learning an about Kamae (構え) posture is not enough to simply just copy Kamae (構え) posture. Copying is Kamae (構え) Posture is only the beginning.
Kamae (構え) Posture is not just about knowing the correct posture. Kamae (構え) teaches structure and body alignment and with knowing proper body alignment you are the power and strength behind your Waza (技) technique. So, that you have power and the strength in your Waza (技) technique. If you Kamae (構え) is correct then your throws, weapons, punches, and kicks will be effective.
The hand position found in a Kamae (構え) can teach Te-Waza (手技) hand techniques and Uke-Waza (受け技) receiving techniques. Your hands and arms should be alive, relaxed and alert. In Aikido/Aikijujutsu, the limbs are supported through good Kamae (構え) posture and Ki 気 to help strengthen and support the body. Good Kamae is Ki 気 and proper physical body alignment and Posture.
The other lessons of Kamae (構え) is learning about position and space. Kamae (構え) will effect your Maai (間合い) your distance and timing. Kamae (構え) effects Kukan 空虚 empty space or 間隔 interval of time between space. Both should be studied and understood. You can use Kamae (構え) to full the space or leave the space.
Learning Kamae (構え) is also learning to deconstruct your Kamae (構え) and the Uke's Kamae (構え). Every Kamae (構え) has a weakness; learn the weakness. This is a break in these structure through striking or throwing you break structure. Know where to throw and where striking is also learning proper Waza (技) technique of moving through states of balance and Kuzushi (崩し) unbalances moments in time and space for both tori and uke. (striking, grappling, etc...).
Kamae (構え) has many lessons This is also Kihon (基本) too.