Leg day is seriously overrated. What should be highly rated depends only on your own personal ideals and goals.
There is no magic involved in doing squats. Squats are not important, unless you re planning to compete in... Squatting. Deadlift is not an important exercise, unless you're planning to compete in... Yes, deadlifting. There is no king of exercises. There are no absolutely essential exercises that "has to" be involved in your workout routine.
There is no absolutely true definition of strength. You can build muscles lifting light weights - and you can do it lifting heavy weights.
You don't need protein powder to build an excellent physique. You don't need creatine. You don't need to eat six times a day. You don't need cardio to get shredded, ripped or cut. You don't need any supplements at all; you can develop an extremely muscular and strong body without it.