In the bible it's written that God created man in his own image, meaning he created only us.
Can it explain the reason why we haven't found life on other planets maybe because threre isn't any?
I can see 2 reasons why we haven't succeeded in finding life on other planets:
1. Life was created exclusively on this planet by God.
2. The conditions required for life to form are very rare and life has formed in just a few places.
This question contains a mix of scientific, philosophical and theological questions. I will address them seperately.
1. From the standpoint of science, we don't know as yet whether life exists on other planets. It is now clearly known by science that other planets besides the ones in our solar system exist, and detecting them is now fairly routine (the observatory I volunteer at has detected one of about five Jupiter masses using microlensing techniques). However, few of these planets seem suitable habitats for life as many have the mass of Jupiter or are larger and orbit very closely to their parent star, sometimes much closer than Mercury's distance from the Sun.
There are promising missions coming up which should help us narrow down the potential range of planets which might have life. It is likely of the planets detected and we will detect, only a fairly small percentage will be suitable for life. It is fairly easy though to extrapolate from the known numbers of statistics that it is certainly possible there are millions of planets and their moons in the galaxy which might be habitable, and billions or trillions of such habitable planets might exist in the universe.
As life has arisen on Earth through evolution, from a scientific point of view, there is nothing (at least as far as is known) that should prevent life arising elsewhere in the cosmos. However, we don't know at this point in time whether life has only ever arisen on Earth. There is a lot of evidence which suggests the precursors of life, like organic molecules (which are often found in dust clouds), water, suitable planets, etc are fairly common in the universe. But complex life is fragile and easily destroyed, and the evolution of intelligent life especially seems highly improbable and frought with many risks. It seems on Earth in all the 4.6 billion years of the planet's history, sentient life capable of using technology has only arisen just once (maybe a few times if you include tool use among animal species). This in itself suggests intelligent beings, if any exist besides us, are rare.
I think life is likely to exist elsewhere in the universe. I think the discovery of extrasolar planets in such numbers strongly improves the chances of life arising elsewhere in the universe. But I think there are compelling
scientific reasons, given in good books on the subject, which suggest intelligent life is rare because its evolution depends on many contigent factors 'working' together in a fortunate way to allow intelligence to emerge.
2. Philosophically speaking, I don't see any reason why intelligent life should not exist. The universe does not seem to have an inbuilt teleology towards or against life, but there does seem to be a set of pathways which allow complex systems to emerge from simple precursors (DNA and RNA) based on fairly straightforward chemistry. It seems as though life is a 'natural' development from the laws of physics, chemistry, and time. But there are also many contingent factors which indicate life cannot exist unless certain pre-conditions are met, some of them relating to the strength of certain forces, the values of certain constants, and so on. Some have argued this indicates there is 'intelligent design' or 'fine-tuning' in the universe, perhaps either at the hands of an intelligent creator who wants to instantiate a universe which allows for the possibility of sentient, free beings to exist (as theists like Keith Ward argue), or maybe our universe is just a 'lucky' pick out of an infinite number of different worlds which exist (multiverse theory), or it is just brute, random fact and there is nothing more to it.
Philosophically speaking, I don't see anything repugnant about accepting there is life elsewhere in the universe. On Earth we co-exist with millions of species of creature who are just as 'alien' as anything we could meet elsewhere. Why could we not accept evolution can do the same on other planets elsewhere in the universe, when the evidence indicates the laws of nature apply universally through the universe at all times and places?
3. Theologically speaking, I don't see an issue with aliens. The Bible does only mention two orders of beings besides God, humans and angels. However even classical theists like Augustine and Aquinas accepted that God could have made other worlds, including worlds better than this one, if he had so chosen. Only Leibniz seemed to argue God could only create this universe, as it was the 'best of all possible worlds' and most fitting with divine justice and wisdom. The doctrine of the incarnation relates to the notion of mankind needing redemption from original sin, which is achieved by Christ's atoning and sacrificial death on the cross. When the merits of this act are appropriated by faith in humans, they become justified in the sight of God and also adopted heirs of God's kingdom. But Aquinas argued quite interestingly God could have redeemed humanity without needing the incarnation or the death of Christ. Classical theism leaves plenty of room, thanks to God's omnipotence, to permit God to choose any kind of world he chooses to make (so long as logical contradiction is not involved). God could also achieve redemption of other beings by other methods, perhaps unknown and unknowable to us.
The main problem with the theological view is God seems very concerned over human beings, who are really tiny, petty creatures in the cosmic scheme of things. Blaise Pascal rightly felt fear before the universe, which seems infinite on the micro-scale and infinite on the macro-scale, and pins human beings between two gigantic abysses in a lonely and perhaps meaningless universe where the divine does not seem to be evident. The view of humans in the Bible seems very narrow and anthropocentric and does not do justice to the immense range of living creatures on Earth (30 million species) as well as the immensity of the wider universe, unless perhaps somehow the incarnation involves and redeems them as well. Why should God be so concerned over human beings, and not say, bacteria, gibbons, monkeys and chickens? Why should an infinite, omnipotent and omniescent being, powerful enough to make an entire universe, worry about tiny, petty creatures like humans, any more than we worry about mites, fleas and bacteria? I think this is quite a challenging question to consider, if you are a theologian or believer.