Animals have no choice but compete but do humans need to? Of course yes but to what extent and how is what I mean. And certainly animals too cooperate to an extent both with members of their own species and also other species.
If I understand Libertarianism correctly, its support for competition and free markets is because such an environment maximizes individual liberty, which is the ultimate end for this school of thought as the name itself suggests. And so even to the most diehard supporters of free markets, competition is not an end but only an instrument for achieving a higher end. Of course when it fails to do that the people from this school will say that even if free market competition fails to deliver the best outcome that doesn't mean government intervention can do better and might likely do even worse and they end up arguing for competition anyway. For its cousin, the Utilitarians too, competition is an instrument to achieving a higher end but that end is some fuzzy notion of aggregate well being and they would be willing to take away some liberties for the larger social good however they conceive it.
As for the socialists and communists, well unfortunately, my economics education, was largely neoclassical (evident from my lumping the two together), and did not expose me to as much of it as the former or any of the heterodox schools with the exception of ecological economics and so I am still educating myself. But in my limited understanding competition seems a more difficult theme to integrate into the socialist conception compared to with Libertarianism or Utilitarianism for it is more about the collective. However, I am sure for socialists too it has to be an instrument to a higher end if at all. So competition obviously has a lot going for it but my aim here is to present a few reasons as to why we need to be less sanguine about espousing it carelessly.
Merits of competition
First and foremost is that the very notion of competition implies fairness. As someone who loves sports, I immediately associate it with competition in sports where everyone plays by the same rules, at least when a million camera's on them
Second is the slightly more sophisticated but in practice more bastardized idea of efficiency. Efficiency is simply about getting the most out of what we put it in - effort, time or resources with the corollary being inefficient implies all sorts of things such as lazy, slow, wasteful and incompetent. In an economic sense, competitive markets are efficient of course given some ideal conditions that dont exist in real world.
Third, competition is about overcoming struggle. It is only when you overcome struggle you get better. And this is intrinsically good in addition to being instrumentally good for learning to overcome future struggles. It is intrinsically good for one's own fulfillment or realization of the purpose of life. While we might all seek pleasure, we also value that which is earned by overcoming hardship more. We dont simply want to live in a pleasure machine like Nozick argued. A similar expression from John Stuart Mill is - "It is better to be a human being dissatisfied than a pig satisfied; better to be Socrates dissatisfied than a fool satisfied. And if the fool, or the pig, is of a different opinion, it is only because they only know their own side of the question.” This is not to say the life of a pig is free of struggle.
Among these attributes of competition, I put fairness and overcoming struggle above efficiency because it is not per se about outcomes or consequences but seems inherently or intrinsically proper regardless of outcomes. That what is fair or just leads to better longer run consequences is only an instrumental reason for what is right and not the intrinsic reason for why what is fair is what is right. As someone who has been exposed to Vedanta , it is consistent with the philosophy of Nishkama Karma expounded in the Bhagavad Gita. In fact most people who are consequentialists will prefer that the right outcomes also result from a fair process. This is why we tolerate democratic processes and a legal system based on innocent until proven guilty even when these occasionally seem to throw up unpalatable outcomes. With fairness, the outcome is endogenous while the process is exogenous.
In contrast, under the notion of efficiency, the outcome or end is exogenous while the process is endogenous which means one could resort to any means if the end goal is desirable or virtuous. It is what we seek to achieve efficiently (in the case of economics it is some fuzzy notion of overall welfare, often reduced by the mediocre or selfish, which is not all but most who have been exposed to some economics unfortunately, to something as crude as GDP). For economists, markets foster competition and competition leads to efficiency and efficiency means maximizing overall welfare for efficiency means we bake the biggest pie possible and a bigger pie also means we can have more redistribution.
The downsides of competition
The real world of course is more messy compared to the abstract and theoretical world which is necessary. It is important not to miss the forest for the trees but you cannot also describe a forest without understanding trees. So the merits often tend to be reductionistic and general while the demerits arise from the nuances and complexity of the real world.
1. Competition is not fair when there are inequities to begin with. If you are born less lucky (in a poor household or a household that is less than desirable)
2. Competition is not efficient if conditions are not right. Asymmetric information, unpriced bads (like pollution) and goods (like knowledge production), monopolies, etc. If such conditions are not rectified then unfettered competition will not produce the best outcomes
3. As to what is worth competing for is something that individuals and society needs to determine for themselves. This requires wisdom, experience, judgement, developing one's own ethics and morals
4. There is little empirical evidence that the greatest of advances that have been made technologically or socially would not have resulted without people competing to succeed and certainly a lot of it can be put down to curiosity (for inventions and discoveries prior to 20th century) and in recent times the biggest ones are due to public investment.
5. Markets are rarely competitive at least for the most important things that matter in life - health care (we know what coke cola costs before you buy but no one can tell what a bandaid will cost in a hospital), education (if your parents aren't wealthy enough to rent let alone buy a home in a good school district, your life prospects get cut even before the umbilical cord is severed upon your emergence), safety (last I checked we depend on publicly funded police and fire services), being able to travel (dont see any real competition - cars don't really compete with air travel which does not compete with ships), energy (your electricity supplier is a local monopoly and oil markets are not) and certainly not housing (havent you heard the cliche no two homes are same!). For everything else there is the mathematically elegant world that one is taught in Economics 101.
6. Everyone is trying to escape it. But the ultimate indictment is that no one wants to keep competing all the time. Even when not doing anything unfair to not compete, people are trying to escape or eliminate it. When you combine this with the fact that not all people may have the same resources to compete it is de facto not competition. In sport, successful sportsmen are able to hire more help - trainers, coaching, equipment, diet etc. In education, people hire tutors. In research, they get access to better equipment and data and design costlier experiments. In business, there is branding. Even in Academia which I know a little bit about people are trying to differentiate themselves which actually avoid competing or at least intended to convey they are not in competition or there is no competition.