I generally agree with that, though I think carbon-based and breathing oxygen is taking it a bit too far, could be silicon-based. And not even all organisms on Earth need oxygen.
Certainly silicon-based life may be possible (and I actually have a few ideas for such life-forms that I am fond of), but from what I understand, they are far less likely to ever occur than carbon-based life, for two reasons. First, carbon reacts with the necessary compounds more readily than silicon, so if carbon is available than it will replace silicon (and as such carbon would be toxic to silicon-based life). Second, silicon reacts more slowly than carbon, so any silicon-based life will grow and develop much more slowly than carbon-based life.
I say breathing oxygen simply because there is a reason almost all life on this planet breathes oxygen (C0
2 has oxygen, so that count for this discussion). I am not sure what it is, but there is certainly a reason for it.
I know, for example, that it is almost impossible that something will depend on nitrogen gas the same way humans depend on oxygen, simply because nitrogen gas is in an extremely low energy state that makes it hard to process. It doesn't want to bond to things the same way that oxygen does (oxygen oxidates things readily, that is why rust happens).
Once you even limit yourself to talking about just carbon-based life, you immediately realize a number of similarities that
must exist among all kinds of life. For example, most if not all carbon based life will use sugar and lipids in their metabolism, for all the same reasons that Earth-based life does. Some things may use other hydrocarbons, like butane or octane, but that would be far less common. Also, while some forms of life can survive on geothermal power, life really needs access to sunlight in order to get enough energy to prosper. Life won't get very far on a planet too distant from a star, even if other conditions are right.
Mortality is probably given, considering that more complex life cannot come into existence ex nihilo, hence some sort of development and evolution must be there, which probably means that something has changed and died to make place for the new beings (though their mortality is not given, considering what technology can do - but they have that concept), which gives us a common psychogical element.
I will go farther and say that mortality
is a given, even with technological assistance. First, true immortality is impossible, since nothing can be totally immune to damage or disease, and the more complex a being is the more it becomes vulnerable to such things (plants are more resistant to damage than humans, but are nowhere near as complex). That leaves the question of aging, but I don't believe it is possible for something to be immune to that either. Ultimately, aging is the total effect of countless errors emerging from the trillions of biological processes occurring throughout the human body at every moment. Since it is impossible for such a process to occur perfectly trillions of times, gradual errors will creep into the system. And any mechanism designed to correct these gradual errors will itself need to run trillions of processes, which themselves are vulnerable to error. A machine designed to keep something from aging will eventually age and wear down itself. Considering that even ridiculously simple things like cars and computers have vastly shorter lifespans than humans, there is no reason to suspect that a much more complicated machine will work more efficiently.
Possibly even resource conflicts (fighting over food), hence the concept of conflict and war.
No possibly about this. Resources are finite, and there will always be competition over them. The nature of the resource and the nature of the competition varies greatly, but the basic concept is universal. While I will not say that this means war is universal, it does mean that concepts like the predator/prey relationship, the idea of survival of the fittest, competition for sunlight, etc, are all important.
Movement: You can move through gas, liquids, and solids - flying, swimming, burrowing and move on transitions - that's some form of wheel, rolling, crawling or leg, we haven't found much else that works.
I am skeptical of the wheel idea (if it were possible, something on Earth would have done so already), but other than that I agree.
Fingers: If they want to build and manipulate stuff, they need some sorf of instrument, it's just like that. Could be pincers, suckers, whatever, but it must have relatively fine control.
I will put this more as an aspect of intelligent alien life, but yeah, this is true. The evolutionary need for advanced intelligence goes hand in hand with manipulating the outside world and communication skills. There is no association between intelligence and being bipedal (hominids learned to walk
long before they got smart), but there is one between being intelligent, having dextrous hands used to build things, and being able to talk.
Not a bad list, really, but there are certainly a few more that you are missing.
First off, far and away the clearest thing that you are missing is transmission of genetic material, AKA sex.
This is one of the very first things developed by Earth bacteria billions of years ago, and it has continued since for a very clear reason: things that exchange genetic material evolve much more rapidly than things that do not. The nature of this exchange can probably vary greatly (it would be absurd to think that static male and female genders, as expressed on earth, would be universal), but it
will exist in any kind of complex alien life.
This may not need to be said, but any kind of life needs some way to regulate its internal biochemistry, so any kind of alien life will need to make use of the restroom once in a while.
Also, all the same rules that limit the sizes of creatures will still apply. You can't have a single-celled organism get any bigger than they do on earth because the volume to surface area ratio changes radically, affecting the ability of the organism to move substances across its cell membrane. You won't find an Earth insect as big as a car because its exoskeleton would collapse and it wouldn't be able to process enough oxygen. You can't just radically increase the size of a person, holding proportions the same, or that person's bones would break from the staggering weight (for 2 x height, you get 2 x muscle strength, 4 x bone strength, and 8 x weight). Differing environments, gravity levels, and physiology affect things differently, but there are certain rules that affect them all equally.
There are all kinds of other rules, that should apply, as well. There is a clear advantage to having all of a creature's sensory organs located on a single appendage that can more independently of the main body, for example. Anything that uses electromagnetic waves to see will use a similar spectrum to our eyesight, not something with a wavelength too large to make things out clearly or too small to be easily detected. While it is hard to say what alien language will be like, it will at the very least contain a distinction between objects (nouns) and properties of objects (verbs,/adjectives). There are practical reasons that control all of these and more.
Huh, this post stretched out a bit longer than I thought it would...