Are there limits to what a human is?
The definition of words and the human personality are malleable and their application to their environment is what the user intends them to be. But, and it is a very big but, it doesn’t mean these words or these people can be anything whatsoever, because they are locked into an environment wherein they exist. The term indefinite needs to come into the discussion because it implies that a progress in a certain direction can go forward for a long time and the limit isn’t known or perhaps knowable, just how long that extension is. Infinite implies an unlimited extension, but when the term is applied to a human being it has a wholly different meaning than when it is applied to numbers. One might add another number to any given number without limit, and one might assert that one could add another inch to the height of any given human being, and another and another. That wouldn’t prove possible because the laws of physics would crush and kill people beyond some size. Also, there is doubt that a human genome making a creature the size of a blue whale would possess many characteristics we would call human.
People are infinitely malleable within limits.
Having dismissed the absurd with an absurd stretching of the base concept it becomes advisable to define the boundaries, at least in a general way, within which people are infinitely malleable. People have great variability, but a gold medal winning Olympic weightlifter will never simultaneously become a winning Olympic diver, nor either of them a winning Olympic marathon runner. The demands of the various activities are too different to develop the necessary body and skills simultaneously. Each of these athletes might possibly have succeeded in the alternate sports if they trained from their youth, because people are malleable and the quality for success might reside most of all in personality and opportunity and in top quality reflexes.
Human personality might be at the root of spectacular success.
If it is the personality which is capable of compelling the body to to marvelous things, given the opportunity, then the personality is what we must observe and discern the traits which make it hone a particular quality. In a way it is non-human to choose a rare potential quality and focus all of one’s energy to developing that normally useless ability into a refined skill. In the entirety of the human species there may never have been a need to do multiple twists off of a 10 meter board and slip splash-less into a pool of water. And yet these days doing just that will win a person the world’s acclaim. If through some vagaries of chance a little ripple of random water tossed the gold coin to another, then their lifetime of dedication worked against their general life success. The same personality dedicated to becoming a skilled plumber would more surely have won them the perks of society. The entertainment industry, and sports is part of that industry, has a vast mountain of also-ran performers with little or no reward for the few who do succeed. Several rare things need be aligned before terrific success comes, and perhaps the most critical is opportunity. That essential is under some control. It requires being in the right place at the right time with the right stuff. Each of those can be pre-determined and prepared for; just like a TV show is prepared for, a person’s life events can be molded before they take place. If a person can foresee what is going to be needed at some particular time and place, which often they can, then they can prepare themselves for that event by molding their personality to fit that event. We humans may not be infinitely malleable, but we are usually sufficiently malleable to be successful at what we choose to do.
Decide what you want to do and mold yourself to do that task.